diff --git a/x-pack/plugins/upgrade_assistant/common/get_index_state_from_cluster_state.test.ts b/x-pack/plugins/upgrade_assistant/common/get_index_state_from_cluster_state.test.ts
new file mode 100644
index 00000000000000..1098594a68f8a2
--- /dev/null
+++ b/x-pack/plugins/upgrade_assistant/common/get_index_state_from_cluster_state.test.ts
@@ -0,0 +1,53 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+import { getIndexStateFromClusterState } from './get_index_state_from_cluster_state';
+import { ClusterStateAPIResponse } from './types';
+
+describe('getIndexStateFromClusterState', () => {
+  const indexName = 'indexName';
+  const clusterState: ClusterStateAPIResponse = {
+    metadata: {
+      indices: {},
+      cluster_coordination: {} as any,
+      cluster_uuid: 'test',
+      templates: {} as any,
+    },
+    cluster_name: 'test',
+    cluster_uuid: 'test',
+  };
+
+  afterEach(() => {
+    clusterState.metadata.indices = {};
+  });
+
+  it('correctly extracts state from cluster state', () => {
+    clusterState.metadata.indices[indexName] = { state: 'open' } as any;
+    clusterState.metadata.indices.aTotallyDifferentIndex = { state: 'close' } as any;
+    expect(getIndexStateFromClusterState(indexName, clusterState)).toBe('open');
+  });
+
+  it('correctly extracts state from aliased index in cluster state', () => {
+    clusterState.metadata.indices.aTotallyDifferentName = {
+      state: 'close',
+      aliases: [indexName, 'test'],
+    } as any;
+    clusterState.metadata.indices.aTotallyDifferentName1 = {
+      state: 'open',
+      aliases: ['another', 'test'],
+    } as any;
+
+    expect(getIndexStateFromClusterState(indexName, clusterState)).toBe('close');
+  });
+
+  it('throws if the index name cannot be found in the cluster state', () => {
+    expect(() => getIndexStateFromClusterState(indexName, clusterState)).toThrow('not found');
+    clusterState.metadata.indices.aTotallyDifferentName1 = {
+      state: 'open',
+      aliases: ['another', 'test'],
+    } as any;
+    expect(() => getIndexStateFromClusterState(indexName, clusterState)).toThrow('not found');
+  });
+});
diff --git a/x-pack/plugins/upgrade_assistant/common/get_index_state_from_cluster_state.ts b/x-pack/plugins/upgrade_assistant/common/get_index_state_from_cluster_state.ts
new file mode 100644
index 00000000000000..75b71fee000d4a
--- /dev/null
+++ b/x-pack/plugins/upgrade_assistant/common/get_index_state_from_cluster_state.ts
@@ -0,0 +1,28 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { ClusterStateAPIResponse } from './types';
+
+const checkAllAliases = (
+  indexName: string,
+  clusterState: ClusterStateAPIResponse
+): 'open' | 'close' => {
+  for (const index of Object.values(clusterState.metadata.indices)) {
+    if (index.aliases?.some(alias => alias === indexName)) {
+      return index.state;
+    }
+  }
+
+  throw new Error(`${indexName} not found in cluster state!`);
+};
+
+export const getIndexStateFromClusterState = (
+  indexName: string,
+  clusterState: ClusterStateAPIResponse
+): 'open' | 'close' =>
+  clusterState.metadata.indices[indexName]
+    ? clusterState.metadata.indices[indexName].state
+    : checkAllAliases(indexName, clusterState);
diff --git a/x-pack/plugins/upgrade_assistant/common/types.ts b/x-pack/plugins/upgrade_assistant/common/types.ts
index ceb3a6dd60166f..1114e889882c26 100644
--- a/x-pack/plugins/upgrade_assistant/common/types.ts
+++ b/x-pack/plugins/upgrade_assistant/common/types.ts
@@ -34,6 +34,13 @@ export interface QueueSettings extends SavedObjectAttributes {
 }
 
 export interface ReindexOptions extends SavedObjectAttributes {
+  /**
+   * Whether to treat the index as if it were closed. This instructs the
+   * reindex strategy to first open the index, perform reindexing and
+   * then close the index again.
+   */
+  openAndClose?: boolean;
+
   /**
    * Set this key to configure a reindex operation as part of a
    * batch to be run in series.
@@ -50,7 +57,6 @@ export interface ReindexOperation extends SavedObjectAttributes {
   reindexTaskId: string | null;
   reindexTaskPercComplete: number | null;
   errorMessage: string | null;
-
   // This field is only used for the singleton IndexConsumerType documents.
   runningReindexCount: number | null;
 
@@ -142,6 +148,14 @@ export interface EnrichedDeprecationInfo extends DeprecationInfo {
   index?: string;
   node?: string;
   reindex?: boolean;
+  /**
+   * Indicate what blockers have been detected for calling reindex
+   * against this index.
+   *
+   * @remark
+   * In future this could be an array of blockers.
+   */
+  blockerForReindexing?: 'index-closed'; // 'index-closed' can be handled automatically, but requires more resources, user should be warned
 }
 
 export interface UpgradeAssistantStatus {
@@ -149,3 +163,42 @@ export interface UpgradeAssistantStatus {
   cluster: EnrichedDeprecationInfo[];
   indices: EnrichedDeprecationInfo[];
 }
+
+export interface ClusterStateIndexAPIResponse {
+  state: 'open' | 'close';
+  settings: {
+    index: {
+      verified_before_close: string;
+      search: {
+        throttled: string;
+      };
+      number_of_shards: string;
+      provided_name: string;
+      frozen: string;
+      creation_date: string;
+      number_of_replicas: string;
+      uuid: string;
+      version: {
+        created: string;
+      };
+    };
+  };
+  mappings: any;
+  aliases: string[];
+}
+
+export interface ClusterStateAPIResponse {
+  cluster_name: string;
+  cluster_uuid: string;
+  metadata: {
+    cluster_uuid: string;
+    cluster_coordination: {
+      term: number;
+      last_committed_config: string[];
+      last_accepted_config: string[];
+      voting_config_exclusions: [];
+    };
+    templates: any;
+    indices: { [indexName: string]: ClusterStateIndexAPIResponse };
+  };
+}
diff --git a/x-pack/plugins/upgrade_assistant/public/application/app_context.tsx b/x-pack/plugins/upgrade_assistant/public/application/app_context.tsx
index 1ae9dabd69481b..11c88a52ea24e0 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/app_context.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/app_context.tsx
@@ -3,12 +3,13 @@
  * or more contributor license agreements. Licensed under the Elastic License;
  * you may not use this file except in compliance with the Elastic License.
  */
-import { HttpSetup } from 'src/core/public';
+import { DocLinksStart, HttpSetup } from 'src/core/public';
 import React, { createContext, useContext } from 'react';
 
 export interface ContextValue {
   http: HttpSetup;
   isCloudEnabled: boolean;
+  docLinks: DocLinksStart;
 }
 
 export const AppContext = createContext<ContextValue>({} as any);
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs.tsx
index 43ec5554aaaeef..77ee3448cd06de 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs.tsx
@@ -14,7 +14,8 @@ import {
   EuiTabbedContent,
   EuiTabbedContentTab,
 } from '@elastic/eui';
-import { FormattedMessage, injectI18n } from '@kbn/i18n/react';
+import { i18n } from '@kbn/i18n';
+import { FormattedMessage } from '@kbn/i18n/react';
 import { HttpSetup } from 'src/core/public';
 
 import { UpgradeAssistantStatus } from '../../../common/types';
@@ -38,9 +39,11 @@ interface TabsState {
   clusterUpgradeState: ClusterUpgradeState;
 }
 
-type Props = ReactIntl.InjectedIntlProps & { http: HttpSetup };
+interface Props {
+  http: HttpSetup;
+}
 
-export class UpgradeAssistantTabsUI extends React.Component<Props, TabsState> {
+export class UpgradeAssistantTabs extends React.Component<Props, TabsState> {
   constructor(props: Props) {
     super(props);
     this.state = {
@@ -172,7 +175,6 @@ export class UpgradeAssistantTabsUI extends React.Component<Props, TabsState> {
   };
 
   private get tabs() {
-    const { intl } = this.props;
     const { loadingError, loadingState, checkupData } = this.state;
     const commonProps: UpgradeAssistantTabProps = {
       loadingError,
@@ -186,24 +188,21 @@ export class UpgradeAssistantTabsUI extends React.Component<Props, TabsState> {
     return [
       {
         id: 'overview',
-        name: intl.formatMessage({
-          id: 'xpack.upgradeAssistant.overviewTab.overviewTabTitle',
+        name: i18n.translate('xpack.upgradeAssistant.overviewTab.overviewTabTitle', {
           defaultMessage: 'Overview',
         }),
         content: <OverviewTab checkupData={checkupData} {...commonProps} />,
       },
       {
         id: 'cluster',
-        name: intl.formatMessage({
-          id: 'xpack.upgradeAssistant.checkupTab.clusterTabLabel',
+        name: i18n.translate('xpack.upgradeAssistant.checkupTab.clusterTabLabel', {
           defaultMessage: 'Cluster',
         }),
         content: (
           <CheckupTab
             key="cluster"
             deprecations={checkupData ? checkupData.cluster : undefined}
-            checkupLabel={intl.formatMessage({
-              id: 'xpack.upgradeAssistant.tabs.checkupTab.clusterLabel',
+            checkupLabel={i18n.translate('xpack.upgradeAssistant.tabs.checkupTab.clusterLabel', {
               defaultMessage: 'cluster',
             })}
             {...commonProps}
@@ -212,16 +211,14 @@ export class UpgradeAssistantTabsUI extends React.Component<Props, TabsState> {
       },
       {
         id: 'indices',
-        name: intl.formatMessage({
-          id: 'xpack.upgradeAssistant.checkupTab.indicesTabLabel',
+        name: i18n.translate('xpack.upgradeAssistant.checkupTab.indicesTabLabel', {
           defaultMessage: 'Indices',
         }),
         content: (
           <CheckupTab
             key="indices"
             deprecations={checkupData ? checkupData.indices : undefined}
-            checkupLabel={intl.formatMessage({
-              id: 'xpack.upgradeAssistant.checkupTab.indexLabel',
+            checkupLabel={i18n.translate('xpack.upgradeAssistant.checkupTab.indexLabel', {
               defaultMessage: 'index',
             })}
             showBackupWarning
@@ -249,5 +246,3 @@ export class UpgradeAssistantTabsUI extends React.Component<Props, TabsState> {
     this.setState({ telemetryState: TelemetryState.Complete });
   }
 }
-
-export const UpgradeAssistantTabs = injectI18n(UpgradeAssistantTabsUI);
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/cell.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/cell.tsx
index 879bb695ca60af..6eaa0de530673f 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/cell.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/cell.tsx
@@ -18,6 +18,7 @@ import {
 import { FormattedMessage } from '@kbn/i18n/react';
 import { ReindexButton } from './reindex';
 import { AppContext } from '../../../../app_context';
+import { EnrichedDeprecationInfo } from '../../../../../../common/types';
 
 interface DeprecationCellProps {
   items?: Array<{ title?: string; body: string }>;
@@ -26,6 +27,7 @@ interface DeprecationCellProps {
   headline?: string;
   healthColor?: string;
   children?: ReactNode;
+  reindexBlocker?: EnrichedDeprecationInfo['blockerForReindexing'];
 }
 
 /**
@@ -38,6 +40,7 @@ export const DeprecationCell: FunctionComponent<DeprecationCellProps> = ({
   docUrl,
   items = [],
   children,
+  reindexBlocker,
 }) => (
   <div className="upgDeprecationCell">
     <EuiFlexGroup responsive={false} wrap alignItems="baseline">
@@ -79,7 +82,14 @@ export const DeprecationCell: FunctionComponent<DeprecationCellProps> = ({
       {reindexIndexName && (
         <EuiFlexItem grow={false}>
           <AppContext.Consumer>
-            {({ http }) => <ReindexButton indexName={reindexIndexName} http={http} />}
+            {({ http, docLinks }) => (
+              <ReindexButton
+                docLinks={docLinks}
+                reindexBlocker={reindexBlocker}
+                indexName={reindexIndexName}
+                http={http}
+              />
+            )}
           </AppContext.Consumer>
         </EuiFlexItem>
       )}
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/index_table.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/index_table.tsx
index 5506528a3ded09..19767c34a1b064 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/index_table.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/index_table.tsx
@@ -11,12 +11,14 @@ import { EuiBasicTable } from '@elastic/eui';
 import { injectI18n } from '@kbn/i18n/react';
 import { ReindexButton } from './reindex';
 import { AppContext } from '../../../../app_context';
+import { EnrichedDeprecationInfo } from '../../../../../../common/types';
 
 const PAGE_SIZES = [10, 25, 50, 100, 250, 500, 1000];
 
 export interface IndexDeprecationDetails {
   index: string;
   reindex: boolean;
+  blockerForReindexing?: EnrichedDeprecationInfo['blockerForReindexing'];
   details?: string;
 }
 
@@ -68,9 +70,10 @@ export class IndexDeprecationTableUI extends React.Component<
       },
     ];
 
-    if (this.actionsColumn) {
-      // @ts-ignore
-      columns.push(this.actionsColumn);
+    const actionsColumn = this.generateActionsColumn();
+
+    if (actionsColumn) {
+      columns.push(actionsColumn as any);
     }
 
     const sorting = {
@@ -134,7 +137,7 @@ export class IndexDeprecationTableUI extends React.Component<
     return { totalItemCount, pageSizeOptions, hidePerPageOptions: false };
   }
 
-  private get actionsColumn() {
+  private generateActionsColumn() {
     // NOTE: this naive implementation assumes all indices in the table are
     // should show the reindex button. This should work for known usecases.
     const { indices } = this.props;
@@ -148,7 +151,16 @@ export class IndexDeprecationTableUI extends React.Component<
           render(indexDep: IndexDeprecationDetails) {
             return (
               <AppContext.Consumer>
-                {({ http }) => <ReindexButton indexName={indexDep.index!} http={http} />}
+                {({ http, docLinks }) => {
+                  return (
+                    <ReindexButton
+                      docLinks={docLinks}
+                      reindexBlocker={indexDep.blockerForReindexing}
+                      indexName={indexDep.index!}
+                      http={http}
+                    />
+                  );
+                }}
               </AppContext.Consumer>
             );
           },
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.test.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.test.tsx
index a1e173737bab06..606faf52b8e2bd 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.test.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.test.tsx
@@ -23,29 +23,29 @@ describe('DeprecationList', () => {
 
     test('shows simple messages when index field is not present', () => {
       expect(shallow(<DeprecationList {...defaultProps} />)).toMatchInlineSnapshot(`
-<div>
-  <SimpleMessageDeprecation
-    deprecation={
-      Object {
-        "level": "warning",
-        "message": "Issue 1",
-        "url": "",
-      }
-    }
-    key="Issue 1"
-  />
-  <SimpleMessageDeprecation
-    deprecation={
-      Object {
-        "level": "warning",
-        "message": "Issue 1",
-        "url": "",
-      }
-    }
-    key="Issue 1"
-  />
-</div>
-`);
+        <div>
+          <SimpleMessageDeprecation
+            deprecation={
+              Object {
+                "level": "warning",
+                "message": "Issue 1",
+                "url": "",
+              }
+            }
+            key="Issue 1"
+          />
+          <SimpleMessageDeprecation
+            deprecation={
+              Object {
+                "level": "warning",
+                "message": "Issue 1",
+                "url": "",
+              }
+            }
+            key="Issue 1"
+          />
+        </div>
+      `);
     });
 
     test('shows index deprecation when index field is present', () => {
@@ -59,31 +59,33 @@ describe('DeprecationList', () => {
       };
       const wrapper = shallow(<DeprecationList {...props} />);
       expect(wrapper).toMatchInlineSnapshot(`
-<IndexDeprecation
-  deprecation={
-    Object {
-      "index": "0",
-      "level": "warning",
-      "message": "Issue 1",
-      "url": "",
-    }
-  }
-  indices={
-    Array [
-      Object {
-        "details": undefined,
-        "index": "0",
-        "reindex": false,
-      },
-      Object {
-        "details": undefined,
-        "index": "1",
-        "reindex": false,
-      },
-    ]
-  }
-/>
-`);
+        <IndexDeprecation
+          deprecation={
+            Object {
+              "index": "0",
+              "level": "warning",
+              "message": "Issue 1",
+              "url": "",
+            }
+          }
+          indices={
+            Array [
+              Object {
+                "blockerForReindexing": undefined,
+                "details": undefined,
+                "index": "0",
+                "reindex": false,
+              },
+              Object {
+                "blockerForReindexing": undefined,
+                "details": undefined,
+                "index": "1",
+                "reindex": false,
+              },
+            ]
+          }
+        />
+      `);
     });
   });
 
@@ -98,31 +100,31 @@ describe('DeprecationList', () => {
 
     test('shows detailed messages', () => {
       expect(shallow(<DeprecationList {...defaultProps} />)).toMatchInlineSnapshot(`
-<div>
-  <MessageDeprecation
-    deprecation={
-      Object {
-        "index": "index1",
-        "level": "warning",
-        "message": "Issue 1",
-        "url": "",
-      }
-    }
-    key="Issue 1"
-  />
-  <MessageDeprecation
-    deprecation={
-      Object {
-        "index": "index1",
-        "level": "warning",
-        "message": "Issue 2",
-        "url": "",
-      }
-    }
-    key="Issue 2"
-  />
-</div>
-`);
+        <div>
+          <MessageDeprecation
+            deprecation={
+              Object {
+                "index": "index1",
+                "level": "warning",
+                "message": "Issue 1",
+                "url": "",
+              }
+            }
+            key="Issue 1"
+          />
+          <MessageDeprecation
+            deprecation={
+              Object {
+                "index": "index1",
+                "level": "warning",
+                "message": "Issue 2",
+                "url": "",
+              }
+            }
+            key="Issue 2"
+          />
+        </div>
+      `);
     });
   });
 });
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.tsx
index a46bc0d12fad41..ab71972f361ea2 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/list.tsx
@@ -32,6 +32,7 @@ const MessageDeprecation: FunctionComponent<{ deprecation: EnrichedDeprecationIn
 
   return (
     <DeprecationCell
+      reindexBlocker={deprecation.blockerForReindexing}
       headline={deprecation.message}
       healthColor={COLOR_MAP[deprecation.level]}
       reindexIndexName={deprecation.reindex ? deprecation.index! : undefined}
@@ -53,7 +54,13 @@ const SimpleMessageDeprecation: FunctionComponent<{ deprecation: EnrichedDepreca
     items.push({ body: deprecation.details });
   }
 
-  return <DeprecationCell items={items} docUrl={deprecation.url} />;
+  return (
+    <DeprecationCell
+      reindexBlocker={deprecation.blockerForReindexing}
+      items={items}
+      docUrl={deprecation.url}
+    />
+  );
 };
 
 interface IndexDeprecationProps {
@@ -89,6 +96,7 @@ export const DeprecationList: FunctionComponent<{
       index: dep.index!,
       details: dep.details,
       reindex: dep.reindex === true,
+      blockerForReindexing: dep.blockerForReindexing,
     }));
     return <IndexDeprecation indices={indices} deprecation={deprecations[0]} />;
   } else if (currentGroupBy === GroupByOption.index) {
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/button.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/button.tsx
index 30b46e0c15213e..3738e265515a0d 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/button.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/button.tsx
@@ -6,12 +6,17 @@
 
 import { set } from 'lodash';
 import React, { Fragment, ReactNode } from 'react';
+import { i18n } from '@kbn/i18n';
 import { Subscription } from 'rxjs';
 
-import { EuiButton, EuiLoadingSpinner } from '@elastic/eui';
+import { EuiButton, EuiLoadingSpinner, EuiText, EuiToolTip } from '@elastic/eui';
 import { FormattedMessage } from '@kbn/i18n/react';
-import { HttpSetup } from 'src/core/public';
-import { ReindexStatus, UIReindexOption } from '../../../../../../../common/types';
+import { DocLinksStart, HttpSetup } from 'src/core/public';
+import {
+  EnrichedDeprecationInfo,
+  ReindexStatus,
+  UIReindexOption,
+} from '../../../../../../../common/types';
 import { LoadingState } from '../../../../types';
 import { ReindexFlyout } from './flyout';
 import { ReindexPollingService, ReindexState } from './polling_service';
@@ -19,6 +24,8 @@ import { ReindexPollingService, ReindexState } from './polling_service';
 interface ReindexButtonProps {
   indexName: string;
   http: HttpSetup;
+  docLinks: DocLinksStart;
+  reindexBlocker?: EnrichedDeprecationInfo['blockerForReindexing'];
 }
 
 interface ReindexButtonState {
@@ -61,7 +68,7 @@ export class ReindexButton extends React.Component<ReindexButtonProps, ReindexBu
   }
 
   public render() {
-    const { indexName } = this.props;
+    const { indexName, reindexBlocker, docLinks } = this.props;
     const { flyoutVisible, reindexState } = this.state;
 
     const buttonProps: any = { size: 's', onClick: this.showFlyout };
@@ -135,12 +142,44 @@ export class ReindexButton extends React.Component<ReindexButtonProps, ReindexBu
       }
     }
 
+    const showIndexedClosedWarning =
+      reindexBlocker === 'index-closed' && reindexState.status !== ReindexStatus.completed;
+
+    if (showIndexedClosedWarning) {
+      buttonProps.color = 'warning';
+      buttonProps.iconType = 'alert';
+    }
+
+    const button = <EuiButton {...buttonProps}>{buttonContent}</EuiButton>;
+
     return (
       <Fragment>
-        <EuiButton {...buttonProps}>{buttonContent}</EuiButton>
+        {showIndexedClosedWarning ? (
+          <EuiToolTip
+            position="top"
+            content={
+              <EuiText size="s">
+                {i18n.translate(
+                  'xpack.upgradeAssistant.checkupTab.reindexing.reindexButton.indexClosedToolTipDetails',
+                  {
+                    defaultMessage:
+                      '"{indexName}" needs to be reindexed, but it is currently closed. The Upgrade Assistant will open, reindex and then close the index. Reindexing may take longer than usual.',
+                    values: { indexName },
+                  }
+                )}
+              </EuiText>
+            }
+          >
+            {button}
+          </EuiToolTip>
+        ) : (
+          button
+        )}
 
         {flyoutVisible && (
           <ReindexFlyout
+            reindexBlocker={reindexBlocker}
+            docLinks={docLinks}
             indexName={indexName}
             closeFlyout={this.closeFlyout}
             reindexState={reindexState}
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.test.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.test.tsx
index b3eefd40f65e4a..b550063af4fe31 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.test.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.test.tsx
@@ -21,6 +21,7 @@ describe('ChecklistFlyout', () => {
     onConfirmInputChange: jest.fn(),
     startReindex: jest.fn(),
     cancelReindex: jest.fn(),
+    renderGlobalCallouts: jest.fn(),
     reindexState: {
       loadingState: LoadingState.Success,
       lastCompletedStep: undefined,
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.tsx
index e1b8f297570781..31ddaba99a896c 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/checklist_step.tsx
@@ -68,17 +68,19 @@ const buttonLabel = (status?: ReindexStatus) => {
  * Displays a flyout that shows the current reindexing status for a given index.
  */
 export const ChecklistFlyoutStep: React.FunctionComponent<{
+  renderGlobalCallouts: () => React.ReactNode;
   closeFlyout: () => void;
   reindexState: ReindexState;
   startReindex: () => void;
   cancelReindex: () => void;
-}> = ({ closeFlyout, reindexState, startReindex, cancelReindex }) => {
+}> = ({ closeFlyout, reindexState, startReindex, cancelReindex, renderGlobalCallouts }) => {
   const { loadingState, status, hasRequiredPrivileges } = reindexState;
   const loading = loadingState === LoadingState.Loading || status === ReindexStatus.inProgress;
 
   return (
     <Fragment>
       <EuiFlyoutBody>
+        {renderGlobalCallouts()}
         <EuiCallOut
           title={
             <FormattedMessage
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/container.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/container.tsx
index fa619140bcd160..be4138b7a29f36 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/container.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/container.tsx
@@ -5,9 +5,20 @@
  */
 
 import React from 'react';
-
-import { EuiFlyout, EuiFlyoutHeader, EuiPortal, EuiTitle } from '@elastic/eui';
+import { DocLinksStart } from 'kibana/public';
+import { i18n } from '@kbn/i18n';
 import { FormattedMessage } from '@kbn/i18n/react';
+import {
+  EuiCallOut,
+  EuiFlyout,
+  EuiFlyoutHeader,
+  EuiLink,
+  EuiPortal,
+  EuiSpacer,
+  EuiTitle,
+} from '@elastic/eui';
+
+import { EnrichedDeprecationInfo, ReindexStatus } from '../../../../../../../../common/types';
 
 import { ReindexState } from '../polling_service';
 import { ChecklistFlyoutStep } from './checklist_step';
@@ -24,12 +35,58 @@ interface ReindexFlyoutProps {
   reindexState: ReindexState;
   startReindex: () => void;
   cancelReindex: () => void;
+  docLinks: DocLinksStart;
+  reindexBlocker?: EnrichedDeprecationInfo['blockerForReindexing'];
 }
 
 interface ReindexFlyoutState {
   currentFlyoutStep: ReindexFlyoutStep;
 }
 
+const getOpenAndCloseIndexDocLink = ({ ELASTIC_WEBSITE_URL, DOC_LINK_VERSION }: DocLinksStart) => (
+  <EuiLink
+    target="_blank"
+    href={`${ELASTIC_WEBSITE_URL}/guide/en/elasticsearch/reference/${DOC_LINK_VERSION}/indices-open-close.html`}
+  >
+    {i18n.translate(
+      'xpack.upgradeAssistant.checkupTab.reindexing.flyout.openAndCloseDocumentation',
+      { defaultMessage: 'documentation' }
+    )}
+  </EuiLink>
+);
+
+const getIndexClosedCallout = (docLinks: DocLinksStart) => (
+  <>
+    <EuiCallOut
+      title={i18n.translate(
+        'xpack.upgradeAssistant.checkupTab.reindexing.flyout.indexClosedCallout.calloutTitle',
+        { defaultMessage: 'Index closed' }
+      )}
+      color="warning"
+      iconType="alert"
+    >
+      <p>
+        <FormattedMessage
+          id="xpack.upgradeAssistant.checkupTab.reindexing.flyout.indexClosedCallout.calloutDetails"
+          defaultMessage="This index is currently closed. The Upgrade Assistant will open, reindex and then close the index. {reindexingMayTakeLongerEmph}. Please see the {docs} for more information."
+          values={{
+            docs: getOpenAndCloseIndexDocLink(docLinks),
+            reindexingMayTakeLongerEmph: (
+              <b>
+                {i18n.translate(
+                  'xpack.upgradeAssistant.checkupTab.reindexing.flyout.indexClosedCallout.calloutDetails.reindexingTakesLongerEmphasis',
+                  { defaultMessage: 'Reindexing may take longer than usual' }
+                )}
+              </b>
+            ),
+          }}
+        />
+      </p>
+    </EuiCallOut>
+    <EuiSpacer size="m" />
+  </>
+);
+
 /**
  * Wrapper for the contents of the flyout that manages which step of the flyout to show.
  */
@@ -48,14 +105,28 @@ export class ReindexFlyout extends React.Component<ReindexFlyoutProps, ReindexFl
   }
 
   public render() {
-    const { closeFlyout, indexName, reindexState, startReindex, cancelReindex } = this.props;
+    const {
+      closeFlyout,
+      indexName,
+      reindexState,
+      startReindex,
+      cancelReindex,
+      reindexBlocker,
+      docLinks,
+    } = this.props;
     const { currentFlyoutStep } = this.state;
 
     let flyoutContents: React.ReactNode;
+
+    const globalCallout =
+      reindexBlocker === 'index-closed' && reindexState.status !== ReindexStatus.completed
+        ? getIndexClosedCallout(docLinks)
+        : undefined;
     switch (currentFlyoutStep) {
       case ReindexFlyoutStep.reindexWarnings:
         flyoutContents = (
           <WarningsFlyoutStep
+            renderGlobalCallouts={() => globalCallout}
             closeFlyout={closeFlyout}
             warnings={reindexState.reindexWarnings!}
             advanceNextStep={this.advanceNextStep}
@@ -65,6 +136,7 @@ export class ReindexFlyout extends React.Component<ReindexFlyoutProps, ReindexFl
       case ReindexFlyoutStep.checklist:
         flyoutContents = (
           <ChecklistFlyoutStep
+            renderGlobalCallouts={() => globalCallout}
             closeFlyout={closeFlyout}
             reindexState={reindexState}
             startReindex={startReindex}
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warning_step.test.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warning_step.test.tsx
index fddbe84e284616..318d2bc7baffef 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warning_step.test.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warning_step.test.tsx
@@ -16,6 +16,7 @@ describe('WarningsFlyoutStep', () => {
     advanceNextStep: jest.fn(),
     warnings: [ReindexWarning.allField, ReindexWarning.booleanFields],
     closeFlyout: jest.fn(),
+    renderGlobalCallouts: jest.fn(),
   };
 
   it('renders', () => {
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warnings_step.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warnings_step.tsx
index 643dd2e9b6efc6..4e296aca3d0b70 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warnings_step.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/flyout/warnings_step.tsx
@@ -62,6 +62,7 @@ const WarningCheckbox: React.FunctionComponent<{
 );
 
 interface WarningsConfirmationFlyoutProps {
+  renderGlobalCallouts: () => React.ReactNode;
   closeFlyout: () => void;
   warnings: ReindexWarning[];
   advanceNextStep: () => void;
@@ -91,7 +92,7 @@ export class WarningsFlyoutStep extends React.Component<
   }
 
   public render() {
-    const { warnings, closeFlyout, advanceNextStep } = this.props;
+    const { warnings, closeFlyout, advanceNextStep, renderGlobalCallouts } = this.props;
     const { checkedIds } = this.state;
 
     // Do not allow to proceed until all checkboxes are checked.
@@ -100,6 +101,7 @@ export class WarningsFlyoutStep extends React.Component<
     return (
       <Fragment>
         <EuiFlyoutBody>
+          {renderGlobalCallouts()}
           <EuiCallOut
             title={
               <FormattedMessage
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/polling_service.ts b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/polling_service.ts
index 6fe6a859057062..bcd3abb98f8d4d 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/polling_service.ts
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/deprecations/reindex/polling_service.ts
@@ -94,6 +94,7 @@ export class ReindexPollingService {
         errorMessage: null,
         cancelLoadingState: undefined,
       });
+
       const data = await this.http.post<ReindexOperation>(
         `/api/upgrade_assistant/reindex/${this.indexName}`
       );
diff --git a/x-pack/plugins/upgrade_assistant/public/plugin.ts b/x-pack/plugins/upgrade_assistant/public/plugin.ts
index 614221272dd5c4..300da4eccae156 100644
--- a/x-pack/plugins/upgrade_assistant/public/plugin.ts
+++ b/x-pack/plugins/upgrade_assistant/public/plugin.ts
@@ -37,8 +37,8 @@ export class UpgradeAssistantUIPlugin implements Plugin {
       }),
       order: 1000,
       async mount({ element }) {
-        const [{ i18n: i18nDep }] = await getStartServices();
-        return renderApp({ element, isCloudEnabled, http, i18n: i18nDep });
+        const [{ i18n: i18nDep, docLinks }] = await getStartServices();
+        return renderApp({ element, isCloudEnabled, http, i18n: i18nDep, docLinks });
       },
     });
   }
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/__snapshots__/es_migration_apis.test.ts.snap b/x-pack/plugins/upgrade_assistant/server/lib/__snapshots__/es_migration_apis.test.ts.snap
index 10f66fd1fc01ac..244fc96acd1943 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/__snapshots__/es_migration_apis.test.ts.snap
+++ b/x-pack/plugins/upgrade_assistant/server/lib/__snapshots__/es_migration_apis.test.ts.snap
@@ -30,6 +30,7 @@ Object {
   ],
   "indices": Array [
     Object {
+      "blockerForReindexing": undefined,
       "details": "[[type: doc, field: spins], [type: doc, field: mlockall], [type: doc, field: node_master], [type: doc, field: primary]]",
       "index": ".monitoring-es-6-2018.11.07",
       "level": "warning",
@@ -38,6 +39,7 @@ Object {
       "url": "https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_mappings_changes.html#_coercion_of_boolean_fields",
     },
     Object {
+      "blockerForReindexing": undefined,
       "details": "[[type: tweet, field: liked]]",
       "index": "twitter",
       "level": "warning",
@@ -46,6 +48,7 @@ Object {
       "url": "https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_mappings_changes.html#_coercion_of_boolean_fields",
     },
     Object {
+      "blockerForReindexing": undefined,
       "details": "[[type: index-pattern, field: notExpandable], [type: config, field: xPackMonitoring:allowReport], [type: config, field: xPackMonitoring:showBanner], [type: dashboard, field: pause], [type: dashboard, field: timeRestore]]",
       "index": ".kibana",
       "level": "warning",
@@ -54,6 +57,7 @@ Object {
       "url": "https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_mappings_changes.html#_coercion_of_boolean_fields",
     },
     Object {
+      "blockerForReindexing": undefined,
       "details": "[[type: doc, field: notify], [type: doc, field: created], [type: doc, field: attach_payload], [type: doc, field: met]]",
       "index": ".watcher-history-6-2018.11.07",
       "level": "warning",
@@ -62,6 +66,7 @@ Object {
       "url": "https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_mappings_changes.html#_coercion_of_boolean_fields",
     },
     Object {
+      "blockerForReindexing": undefined,
       "details": "[[type: doc, field: snapshot]]",
       "index": ".monitoring-kibana-6-2018.11.07",
       "level": "warning",
@@ -70,6 +75,7 @@ Object {
       "url": "https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_mappings_changes.html#_coercion_of_boolean_fields",
     },
     Object {
+      "blockerForReindexing": undefined,
       "details": "[[type: tweet, field: liked]]",
       "index": "twitter2",
       "level": "warning",
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/es_indices_state_check.ts b/x-pack/plugins/upgrade_assistant/server/lib/es_indices_state_check.ts
new file mode 100644
index 00000000000000..9931abf7f416c4
--- /dev/null
+++ b/x-pack/plugins/upgrade_assistant/server/lib/es_indices_state_check.ts
@@ -0,0 +1,36 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { IScopedClusterClient } from 'kibana/server';
+import { getIndexStateFromClusterState } from '../../common/get_index_state_from_cluster_state';
+import { ClusterStateAPIResponse } from '../../common/types';
+
+type StatusCheckResult = Record<string, 'open' | 'close'>;
+
+export const esIndicesStateCheck = async (
+  dataClient: IScopedClusterClient,
+  indices: string[]
+): Promise<StatusCheckResult> => {
+  // According to https://www.elastic.co/guide/en/elasticsearch/reference/7.6/cluster-state.html
+  // The response from this call is considered internal and subject to change. We have an API
+  // integration test for asserting that the current ES version still returns what we expect.
+  // This lives in x-pack/test/upgrade_assistant_integration
+  const clusterState: ClusterStateAPIResponse = await dataClient.callAsCurrentUser(
+    'cluster.state',
+    {
+      index: indices,
+      metric: 'metadata',
+    }
+  );
+
+  const result: StatusCheckResult = {};
+
+  indices.forEach(index => {
+    result[index] = getIndexStateFromClusterState(index, clusterState);
+  });
+
+  return result;
+};
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts b/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts
index 4ab4227ba3e919..89571a4a18231a 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts
@@ -15,9 +15,24 @@ describe('getUpgradeAssistantStatus', () => {
   let deprecationsResponse: DeprecationAPIResponse;
 
   const dataClient = elasticsearchServiceMock.createScopedClusterClient();
-  (dataClient.callAsCurrentUser as jest.Mock).mockImplementation(async (api, { path }) => {
+  (dataClient.callAsCurrentUser as jest.Mock).mockImplementation(async (api, { path, index }) => {
     if (path === '/_migration/deprecations') {
       return deprecationsResponse;
+    } else if (api === 'cluster.state') {
+      return {
+        metadata: {
+          indices: {
+            ...index.reduce((acc: any, i: any) => {
+              return {
+                ...acc,
+                [i]: {
+                  state: 'open',
+                },
+              };
+            }, {}),
+          },
+        },
+      };
     } else if (api === 'indices.getMapping') {
       return {};
     } else {
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.ts b/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.ts
index 68f21c1fd93b56..3381e5506f39a6 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.ts
@@ -8,6 +8,8 @@ import { IScopedClusterClient } from 'src/core/server';
 import { DeprecationAPIResponse } from 'src/legacy/core_plugins/elasticsearch';
 import { EnrichedDeprecationInfo, UpgradeAssistantStatus } from '../../common/types';
 
+import { esIndicesStateCheck } from './es_indices_state_check';
+
 export async function getUpgradeAssistantStatus(
   dataClient: IScopedClusterClient,
   isCloudEnabled: boolean
@@ -20,6 +22,19 @@ export async function getUpgradeAssistantStatus(
   const cluster = getClusterDeprecations(deprecations, isCloudEnabled);
   const indices = getCombinedIndexInfos(deprecations);
 
+  const indexNames = indices.map(({ index }) => index!);
+
+  // If we have found deprecation information for index/indices check whether the index is
+  // open or closed.
+  if (indexNames.length) {
+    const indexStates = await esIndicesStateCheck(dataClient, indexNames);
+
+    indices.forEach(indexData => {
+      indexData.blockerForReindexing =
+        indexStates[indexData.index!] === 'close' ? 'index-closed' : undefined;
+    });
+  }
+
   const criticalWarnings = cluster.concat(indices).filter(d => d.level === 'critical');
 
   return {
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/index_settings.ts b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/index_settings.ts
index f6dc471d0945d3..5722a6c29b68ff 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/index_settings.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/index_settings.ts
@@ -88,6 +88,7 @@ const removeUnsettableSettings = (settings: FlatSettings['settings']) =>
     'index.routing.allocation.initial_recovery._id',
     'index.version.created',
     'index.version.upgraded',
+    'index.verified_before_close',
   ]);
 
 // Use `flow` to pipe the settings through each function.
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.test.ts b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.test.ts
index 4569fdfa33a83b..0a8887083c27e9 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.test.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.test.ts
@@ -51,6 +51,7 @@ describe('ReindexActions', () => {
       expect(client.create).toHaveBeenCalledWith(REINDEX_OP_TYPE, {
         indexName: 'myIndex',
         newIndexName: `reindexed-v${CURRENT_MAJOR_VERSION}-myIndex`,
+        reindexOptions: undefined,
         status: ReindexStatus.inProgress,
         lastCompletedStep: ReindexStep.created,
         locked: null,
@@ -66,6 +67,7 @@ describe('ReindexActions', () => {
       expect(client.create).toHaveBeenCalledWith(REINDEX_OP_TYPE, {
         indexName: '.internalIndex',
         newIndexName: `.reindexed-v${CURRENT_MAJOR_VERSION}-internalIndex`,
+        reindexOptions: undefined,
         status: ReindexStatus.inProgress,
         lastCompletedStep: ReindexStep.created,
         locked: null,
@@ -83,6 +85,7 @@ describe('ReindexActions', () => {
       expect(client.create).toHaveBeenCalledWith(REINDEX_OP_TYPE, {
         indexName,
         newIndexName: `reindexed-v${CURRENT_MAJOR_VERSION}-myIndex`,
+        reindexOptions: undefined,
         status: ReindexStatus.inProgress,
         lastCompletedStep: ReindexStep.created,
         locked: null,
@@ -98,6 +101,7 @@ describe('ReindexActions', () => {
       expect(client.create).toHaveBeenCalledWith(REINDEX_OP_TYPE, {
         indexName: `reindexed-v${PREV_MAJOR_VERSION}-myIndex`,
         newIndexName: `reindexed-v${CURRENT_MAJOR_VERSION}-myIndex`,
+        reindexOptions: undefined,
         status: ReindexStatus.inProgress,
         lastCompletedStep: ReindexStep.created,
         locked: null,
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.ts b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.ts
index 422e78c2f12ad9..81c8f2563a66d9 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_actions.ts
@@ -35,7 +35,7 @@ export interface ReindexActions {
   /**
    * Creates a new reindexOp, does not perform any pre-flight checks.
    * @param indexName
-   * @param opts Options for the reindex operation
+   * @param opts Additional options when creating the reindex operation
    */
   createReindexOp(indexName: string, opts?: ReindexOptions): Promise<ReindexSavedObject>;
 
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.test.ts b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.test.ts
index 886ea6761e3b73..beb7b28e05e97b 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.test.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.test.ts
@@ -841,7 +841,11 @@ describe('reindexService', () => {
     describe('newIndexCreated', () => {
       const reindexOp = {
         id: '1',
-        attributes: { ...defaultAttributes, lastCompletedStep: ReindexStep.newIndexCreated },
+        attributes: {
+          ...defaultAttributes,
+          lastCompletedStep: ReindexStep.newIndexCreated,
+          reindexOptions: { openAndClose: false },
+        },
       } as ReindexSavedObject;
 
       beforeEach(() => {
@@ -957,7 +961,11 @@ describe('reindexService', () => {
     describe('reindexCompleted', () => {
       const reindexOp = {
         id: '1',
-        attributes: { ...defaultAttributes, lastCompletedStep: ReindexStep.reindexCompleted },
+        attributes: {
+          ...defaultAttributes,
+          lastCompletedStep: ReindexStep.reindexCompleted,
+          reindexOptions: { openAndClose: false },
+        },
       } as ReindexSavedObject;
 
       it('switches aliases, sets as complete, and updates lastCompletedStep', async () => {
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.ts b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.ts
index aa91b925b744b2..4cc465e1f10b9c 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/reindexing/reindex_service.ts
@@ -14,6 +14,7 @@ import {
   ReindexStep,
   ReindexWarning,
 } from '../../../common/types';
+
 import {
   generateNewIndexName,
   getReindexWarnings,
@@ -52,7 +53,7 @@ export interface ReindexService {
   /**
    * Creates a new reindex operation for a given index.
    * @param indexName
-   * @param opts
+   * @param opts Additional options when creating a new reindex operation
    */
   createReindexOperation(indexName: string, opts?: ReindexOptions): Promise<ReindexSavedObject>;
 
@@ -314,7 +315,11 @@ export const reindexServiceFactory = (
    * @param reindexOp
    */
   const startReindexing = async (reindexOp: ReindexSavedObject) => {
-    const { indexName } = reindexOp.attributes;
+    const { indexName, reindexOptions } = reindexOp.attributes;
+
+    if (reindexOptions?.openAndClose === true) {
+      await callAsUser('indices.open', { index: indexName });
+    }
 
     const startReindex = (await callAsUser('reindex', {
       refresh: true,
@@ -394,7 +399,7 @@ export const reindexServiceFactory = (
    * @param reindexOp
    */
   const switchAlias = async (reindexOp: ReindexSavedObject) => {
-    const { indexName, newIndexName } = reindexOp.attributes;
+    const { indexName, newIndexName, reindexOptions } = reindexOp.attributes;
 
     const existingAliases = (
       await callAsUser('indices.getAlias', {
@@ -420,6 +425,10 @@ export const reindexServiceFactory = (
       throw error.cannotCreateIndex(`Index aliases could not be created.`);
     }
 
+    if (reindexOptions?.openAndClose === true) {
+      await callAsUser('indices.close', { index: indexName });
+    }
+
     return actions.updateReindexOp(reindexOp, {
       lastCompletedStep: ReindexStep.aliasCreated,
     });
@@ -647,7 +656,7 @@ export const reindexServiceFactory = (
 
         return actions.updateReindexOp(op, {
           status: ReindexStatus.inProgress,
-          reindexOptions: opts,
+          reindexOptions: opts ?? op.attributes.reindexOptions,
         });
       });
     },
diff --git a/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_handler.ts b/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_handler.ts
index 944b4a225d4425..b7569d86795909 100644
--- a/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_handler.ts
+++ b/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_handler.ts
@@ -23,7 +23,10 @@ interface ReindexHandlerArgs {
   licensing: LicensingPluginSetup;
   headers: Record<string, any>;
   credentialStore: CredentialStore;
-  enqueue?: boolean;
+  reindexOptions?: {
+    openAndClose?: boolean;
+    enqueue?: boolean;
+  };
 }
 
 export const reindexHandler = async ({
@@ -34,7 +37,7 @@ export const reindexHandler = async ({
   licensing,
   log,
   savedObjects,
-  enqueue,
+  reindexOptions,
 }: ReindexHandlerArgs): Promise<ReindexOperation> => {
   const callAsCurrentUser = dataClient.callAsCurrentUser.bind(dataClient);
   const reindexActions = reindexActionsFactory(savedObjects, callAsCurrentUser);
@@ -51,8 +54,11 @@ export const reindexHandler = async ({
 
   const existingOp = await reindexService.findReindexOperation(indexName);
 
-  const opts: ReindexOptions | undefined = enqueue
-    ? { queueSettings: { queuedAt: Date.now() } }
+  const opts: ReindexOptions | undefined = reindexOptions
+    ? {
+        openAndClose: reindexOptions.openAndClose,
+        queueSettings: reindexOptions.enqueue ? { queuedAt: Date.now() } : undefined,
+      }
     : undefined;
 
   // If the reindexOp already exists and it's paused, resume it. Otherwise create a new one.
diff --git a/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.test.ts b/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.test.ts
index af4f7f436ec811..dc1516ad765609 100644
--- a/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.test.ts
+++ b/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.test.ts
@@ -20,7 +20,7 @@ const mockReindexService = {
   resumeReindexOperation: jest.fn(),
   cancelReindexing: jest.fn(),
 };
-
+jest.mock('../../lib/es_indices_state_check', () => ({ esIndicesStateCheck: jest.fn() }));
 jest.mock('../../lib/es_version_precheck', () => ({
   versionCheckHandlerWrapper: (a: any) => a,
 }));
@@ -39,6 +39,7 @@ import {
 } from '../../../common/types';
 import { credentialStoreFactory } from '../../lib/reindexing/credential_store';
 import { registerReindexIndicesRoutes } from './reindex_indices';
+import { esIndicesStateCheck } from '../../lib/es_indices_state_check';
 
 /**
  * Since these route callbacks are so thin, these serve simply as integration tests
@@ -56,6 +57,7 @@ describe('reindex API', () => {
   } as any;
 
   beforeEach(() => {
+    (esIndicesStateCheck as jest.Mock).mockResolvedValue({});
     mockRouter = createMockRouter();
     routeDependencies = {
       credentialStore,
@@ -166,7 +168,9 @@ describe('reindex API', () => {
       );
 
       // It called create correctly
-      expect(mockReindexService.createReindexOperation).toHaveBeenCalledWith('theIndex', undefined);
+      expect(mockReindexService.createReindexOperation).toHaveBeenCalledWith('theIndex', {
+        openAndClose: false,
+      });
 
       // It returned the right results
       expect(resp.status).toEqual(200);
@@ -233,7 +237,10 @@ describe('reindex API', () => {
         kibanaResponseFactory
       );
       // It called resume correctly
-      expect(mockReindexService.resumeReindexOperation).toHaveBeenCalledWith('theIndex', undefined);
+      expect(mockReindexService.resumeReindexOperation).toHaveBeenCalledWith('theIndex', {
+        openAndClose: false,
+        queueSettings: undefined,
+      });
       expect(mockReindexService.createReindexOperation).not.toHaveBeenCalled();
 
       // It returned the right results
@@ -262,6 +269,7 @@ describe('reindex API', () => {
 
   describe('POST /api/upgrade_assistant/reindex/batch', () => {
     const queueSettingsArg = {
+      openAndClose: false,
       queueSettings: { queuedAt: expect.any(Number) },
     };
     it('creates a collection of index operations', async () => {
diff --git a/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.ts b/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.ts
index 697b73d8e10f68..0846e6c0d31d3b 100644
--- a/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.ts
+++ b/x-pack/plugins/upgrade_assistant/server/routes/reindex_indices/reindex_indices.ts
@@ -16,6 +16,7 @@ import { LicensingPluginSetup } from '../../../../licensing/server';
 import { ReindexStatus } from '../../../common/types';
 
 import { versionCheckHandlerWrapper } from '../../lib/es_version_precheck';
+import { esIndicesStateCheck } from '../../lib/es_indices_state_check';
 import { reindexServiceFactory, ReindexWorker } from '../../lib/reindexing';
 import { CredentialStore } from '../../lib/reindexing/credential_store';
 import { reindexActionsFactory } from '../../lib/reindexing/reindex_actions';
@@ -107,6 +108,7 @@ export function registerReindexIndicesRoutes(
         response
       ) => {
         const { indexName } = request.params;
+        const indexStates = await esIndicesStateCheck(dataClient, [indexName]);
         try {
           const result = await reindexHandler({
             savedObjects: savedObjectsClient,
@@ -116,6 +118,7 @@ export function registerReindexIndicesRoutes(
             licensing,
             headers: request.headers,
             credentialStore,
+            reindexOptions: { openAndClose: indexStates[indexName] === 'close' },
           });
 
           // Kick the worker on this node to immediately pickup the new reindex operation.
@@ -187,6 +190,7 @@ export function registerReindexIndicesRoutes(
         response
       ) => {
         const { indexNames } = request.body;
+        const indexStates = await esIndicesStateCheck(dataClient, indexNames);
         const results: PostBatchResponse = {
           enqueued: [],
           errors: [],
@@ -201,7 +205,10 @@ export function registerReindexIndicesRoutes(
               licensing,
               headers: request.headers,
               credentialStore,
-              enqueue: true,
+              reindexOptions: {
+                openAndClose: indexStates[indexName] === 'close',
+                enqueue: true,
+              },
             });
             results.enqueued.push(result);
           } catch (e) {
diff --git a/x-pack/test/upgrade_assistant_integration/upgrade_assistant/index.js b/x-pack/test/upgrade_assistant_integration/upgrade_assistant/index.js
index 196e06a61833b9..fa8c3fd99f71d6 100644
--- a/x-pack/test/upgrade_assistant_integration/upgrade_assistant/index.js
+++ b/x-pack/test/upgrade_assistant_integration/upgrade_assistant/index.js
@@ -9,5 +9,6 @@ export default function({ loadTestFile }) {
     this.tags('ciGroup7');
 
     loadTestFile(require.resolve('./reindexing'));
+    loadTestFile(require.resolve('./status'));
   });
 }
diff --git a/x-pack/test/upgrade_assistant_integration/upgrade_assistant/reindexing.js b/x-pack/test/upgrade_assistant_integration/upgrade_assistant/reindexing.js
index a99c02ffef23e7..d2cae9830d31ad 100644
--- a/x-pack/test/upgrade_assistant_integration/upgrade_assistant/reindexing.js
+++ b/x-pack/test/upgrade_assistant_integration/upgrade_assistant/reindexing.js
@@ -8,6 +8,7 @@ import expect from '@kbn/expect';
 
 import { ReindexStatus, REINDEX_OP_TYPE } from '../../../plugins/upgrade_assistant/common/types';
 import { generateNewIndexName } from '../../../plugins/upgrade_assistant/server/lib/reindexing/index_settings';
+import { getIndexStateFromClusterState } from '../../../plugins/upgrade_assistant/common/get_index_state_from_cluster_state';
 
 export default function({ getService }) {
   const supertest = getService('supertest');
@@ -178,6 +179,8 @@ export default function({ getService }) {
         await es.indices.create({ index: test2 });
         await es.indices.create({ index: test3 });
 
+        await es.indices.close({ index: test1 });
+
         const result = await supertest
           .post(`/api/upgrade_assistant/reindex/batch`)
           .set('kbn-xsrf', 'xxx')
@@ -187,6 +190,8 @@ export default function({ getService }) {
         expect(result.body.enqueued.length).to.equal(3);
         expect(result.body.errors.length).to.equal(0);
 
+        const [{ newIndexName: newTest1Name }] = result.body.enqueued;
+
         await assertQueueState(test1, 3);
         await waitForReindexToComplete(test1);
 
@@ -197,6 +202,18 @@ export default function({ getService }) {
         await waitForReindexToComplete(test3);
 
         await assertQueueState(undefined, 0);
+
+        // Check that the closed index is still closed after reindexing
+        const clusterStateResponse = await es.cluster.state({
+          index: newTest1Name,
+          metric: 'metadata',
+        });
+
+        const test1ReindexedState = getIndexStateFromClusterState(
+          newTest1Name,
+          clusterStateResponse
+        );
+        expect(test1ReindexedState).to.be('close');
       } finally {
         await cleanupReindex(test1);
         await cleanupReindex(test2);
diff --git a/x-pack/test/upgrade_assistant_integration/upgrade_assistant/status.ts b/x-pack/test/upgrade_assistant_integration/upgrade_assistant/status.ts
new file mode 100644
index 00000000000000..f38130aa594c19
--- /dev/null
+++ b/x-pack/test/upgrade_assistant_integration/upgrade_assistant/status.ts
@@ -0,0 +1,57 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import expect from '@kbn/expect';
+import { FtrProviderContext } from '../../api_integration/ftr_provider_context';
+import { getIndexStateFromClusterState } from '../../../plugins/upgrade_assistant/common/get_index_state_from_cluster_state';
+
+// eslint-disable-next-line import/no-default-export
+export default function({ getService }: FtrProviderContext) {
+  const esArchiver = getService('esArchiver');
+  const es = getService('es');
+
+  describe('status and _cluster/state contract', () => {
+    beforeEach(async () => {
+      await es.indices.open({ index: '7.0-data' });
+    });
+
+    afterEach(async () => {
+      await es.indices.open({ index: '7.0-data' });
+    });
+
+    // According to https://www.elastic.co/guide/en/elasticsearch/reference/7.6/cluster-state.html
+    // The response from this call is considered internal and subject to change. We check that
+    // the contract has not changed in this integration test.
+    it('the _cluster/state endpoint is still what we expect', async () => {
+      await esArchiver.load('upgrade_assistant/reindex');
+      await es.indices.close({ index: '7.0-data' });
+      const result = await es.cluster.state({
+        index: '7.0-data',
+        metric: 'metadata',
+      });
+
+      try {
+        if (getIndexStateFromClusterState('7.0-data', result.body) === 'close') {
+          return;
+        }
+      } catch (e) {
+        expect().fail(
+          `Can no longer access index open/closed state. Please update Upgrade Assistant checkup. (${e.message})`
+        );
+        return;
+      }
+      expect().fail(
+        `The response contract for _cluster/state metadata has changed. Please update Upgrade Assistant checkup. Received ${JSON.stringify(
+          result,
+          null,
+          2
+        )}.
+
+Expected body.metadata.indices['7.0-data'].state to be "close".`
+      );
+    });
+  });
+}