diff --git a/src/plugins/expressions/common/ast/types.ts b/src/plugins/expressions/common/ast/types.ts
index d5039d0adb3180..09fb4fae3f201e 100644
--- a/src/plugins/expressions/common/ast/types.ts
+++ b/src/plugins/expressions/common/ast/types.ts
@@ -18,7 +18,6 @@
  */
 
 import { ExpressionValue, ExpressionValueError } from '../expression_types';
-import { ExpressionFunction } from '../../common';
 
 export type ExpressionAstNode =
   | ExpressionAstExpression
@@ -48,9 +47,9 @@ export interface ExpressionAstFunctionDebug {
   success: boolean;
 
   /**
-   * Reference to the expression function this AST node represents.
+   * Id of expression function.
    */
-  fn: ExpressionFunction;
+  fn: string;
 
   /**
    * Input that expression function received as its first argument.
diff --git a/src/plugins/expressions/common/execution/execution.test.ts b/src/plugins/expressions/common/execution/execution.test.ts
index 2b8aa4b5e68f09..ff331d7c5ddaff 100644
--- a/src/plugins/expressions/common/execution/execution.test.ts
+++ b/src/plugins/expressions/common/execution/execution.test.ts
@@ -491,7 +491,7 @@ describe('Execution', () => {
         await execution.result;
 
         for (const node of execution.state.get().ast.chain) {
-          expect(node.debug?.fn.name).toBe('add');
+          expect(node.debug?.fn).toBe('add');
         }
       });
 
@@ -667,7 +667,7 @@ describe('Execution', () => {
 
         expect(node2.debug).toMatchObject({
           success: false,
-          fn: expect.any(Object),
+          fn: 'throws',
           input: expect.any(Object),
           args: expect.any(Object),
           error: expect.any(Object),
diff --git a/src/plugins/expressions/common/execution/execution.ts b/src/plugins/expressions/common/execution/execution.ts
index 3533500a2fbc59..d4c9b0a25d45b7 100644
--- a/src/plugins/expressions/common/execution/execution.ts
+++ b/src/plugins/expressions/common/execution/execution.ts
@@ -235,7 +235,7 @@ export class Execution<
           const timeEnd: number = now();
           (link as ExpressionAstFunction).debug = {
             success: true,
-            fn,
+            fn: fn.name,
             input,
             args: resolvedArgs,
             output,
@@ -253,7 +253,7 @@ export class Execution<
         if (this.params.debug) {
           (link as ExpressionAstFunction).debug = {
             success: false,
-            fn,
+            fn: fn.name,
             input,
             args,
             error,