diff --git a/apps/dav/lib/CardDAV/CardDavBackend.php b/apps/dav/lib/CardDAV/CardDavBackend.php
index 51d24351c05b3..b7133c31e9a7f 100644
--- a/apps/dav/lib/CardDAV/CardDavBackend.php
+++ b/apps/dav/lib/CardDAV/CardDavBackend.php
@@ -879,7 +879,7 @@ public function getChangesForAddressBook($addressBookId, $syncToken, $syncLevel,
 		if ($syncToken) {
 			$query = "SELECT `uri`, `operation` FROM `*PREFIX*addressbookchanges` WHERE `synctoken` >= ? AND `synctoken` < ? AND `addressbookid` = ? ORDER BY `synctoken`";
 			if ($limit > 0) {
-				$query .= " LIMIT " . (int)$limit;
+				$query .= " LIMIT " . $limit;
 			}
 
 			// Fetching all changes
diff --git a/apps/dav/lib/Connector/Sabre/SharesPlugin.php b/apps/dav/lib/Connector/Sabre/SharesPlugin.php
index 98458ff8bfa29..cea5f5a9ffdf3 100644
--- a/apps/dav/lib/Connector/Sabre/SharesPlugin.php
+++ b/apps/dav/lib/Connector/Sabre/SharesPlugin.php
@@ -69,7 +69,7 @@ class SharesPlugin extends \Sabre\DAV\ServerPlugin {
 	 */
 	private $userFolder;
 
-	/** @var IShare[] */
+	/** @var IShare[][] */
 	private $cachedShares = [];
 
 	private $cachedFolders = [];
@@ -112,7 +112,11 @@ public function initialize(\Sabre\DAV\Server $server) {
 		$this->server->on('propFind', [$this, 'handleGetProperties']);
 	}
 
-	private function getShare(\OCP\Files\Node $node): array {
+	/**
+	 * @return IShare[]
+	 */
+	private function getSharesForFilesNode(\OCP\Files\Node $node): array {
+		/** @var IShare[] $result */
 		$result = [];
 		$requestedShareTypes = [
 			IShare::TYPE_USER,
@@ -139,6 +143,9 @@ private function getShare(\OCP\Files\Node $node): array {
 		return $result;
 	}
 
+	/**
+	 * @return IShare[][]
+	 */
 	private function getSharesFolder(\OCP\Files\Folder $node): array {
 		return $this->shareManager->getSharesInFolder(
 			$this->userId,
@@ -147,7 +154,10 @@ private function getSharesFolder(\OCP\Files\Folder $node): array {
 		);
 	}
 
-	private function getShares(\Sabre\DAV\INode $sabreNode): array {
+	/**
+	 * @return IShare[]
+	 */
+	private function getSharesForSabreNode(\Sabre\DAV\INode $sabreNode): array {
 		if (isset($this->cachedShares[$sabreNode->getId()])) {
 			$shares = $this->cachedShares[$sabreNode->getId()];
 		} else {
@@ -158,7 +168,7 @@ private function getShares(\Sabre\DAV\INode $sabreNode): array {
 			// if we already cached the folder this file is in we know there are no shares for this file
 			if (array_search($parentPath, $this->cachedFolders) === false) {
 				$node = $this->userFolder->get($sabreNode->getPath());
-				$shares = $this->getShare($node);
+				$shares = $this->getSharesForFilesNode($node);
 				$this->cachedShares[$sabreNode->getId()] = $shares;
 			} else {
 				return [];
@@ -200,7 +210,7 @@ public function handleGetProperties(
 		}
 
 		$propFind->handle(self::SHARETYPES_PROPERTYNAME, function () use ($sabreNode) {
-			$shares = $this->getShares($sabreNode);
+			$shares = $this->getSharesForSabreNode($sabreNode);
 
 			$shareTypes = array_unique(array_map(function (IShare $share) {
 				return $share->getShareType();
@@ -210,7 +220,7 @@ public function handleGetProperties(
 		});
 
 		$propFind->handle(self::SHAREES_PROPERTYNAME, function () use ($sabreNode) {
-			$shares = $this->getShares($sabreNode);
+			$shares = $this->getSharesForSabreNode($sabreNode);
 
 			return new ShareeList($shares);
 		});
diff --git a/apps/dav/lib/Provisioning/Apple/AppleProvisioningPlugin.php b/apps/dav/lib/Provisioning/Apple/AppleProvisioningPlugin.php
index 6e45affb3fe59..e306c2a465542 100644
--- a/apps/dav/lib/Provisioning/Apple/AppleProvisioningPlugin.php
+++ b/apps/dav/lib/Provisioning/Apple/AppleProvisioningPlugin.php
@@ -130,6 +130,7 @@ public function httpGet(RequestInterface $request, ResponseInterface $response):
 		$absoluteURL = $this->urlGenerator->getBaseUrl();
 		$parsedUrl = parse_url($absoluteURL);
 		if (isset($parsedUrl['port'])) {
+			/** @psalm-suppress RedundantCast */
 			$serverPort = (int) $parsedUrl['port'];
 		} else {
 			$serverPort = 443;
diff --git a/apps/files_sharing/lib/Controller/ShareAPIController.php b/apps/files_sharing/lib/Controller/ShareAPIController.php
index e999e5dd4bb7d..12408d8e108fa 100644
--- a/apps/files_sharing/lib/Controller/ShareAPIController.php
+++ b/apps/files_sharing/lib/Controller/ShareAPIController.php
@@ -1147,7 +1147,6 @@ public function updateShare(
 		// NOT A LINK SHARE
 		else {
 			if ($permissions !== null) {
-				$permissions = (int) $permissions;
 				$share->setPermissions($permissions);
 			}
 
diff --git a/apps/theming/lib/IconBuilder.php b/apps/theming/lib/IconBuilder.php
index 68d1ff311fe8e..65b7be430edf4 100644
--- a/apps/theming/lib/IconBuilder.php
+++ b/apps/theming/lib/IconBuilder.php
@@ -198,8 +198,8 @@ public function renderAppIcon($app, $size) {
 		// offset for icon positioning
 		$border_w = (int)($appIconFile->getImageWidth() * 0.05);
 		$border_h = (int)($appIconFile->getImageHeight() * 0.05);
-		$innerWidth = (int)($appIconFile->getImageWidth() - $border_w * 2);
-		$innerHeight = (int)($appIconFile->getImageHeight() - $border_h * 2);
+		$innerWidth = ($appIconFile->getImageWidth() - $border_w * 2);
+		$innerHeight = ($appIconFile->getImageHeight() - $border_h * 2);
 		$appIconFile->adaptiveResizeImage($innerWidth, $innerHeight);
 		// center icon
 		$offset_w = 512 / 2 - $innerWidth / 2;
diff --git a/apps/user_ldap/lib/Access.php b/apps/user_ldap/lib/Access.php
index fc1f2458fd187..f255e344a9838 100644
--- a/apps/user_ldap/lib/Access.php
+++ b/apps/user_ldap/lib/Access.php
@@ -180,7 +180,7 @@ public function getConnection() {
 	 *          array if $attr is empty, false otherwise
 	 * @throws ServerNotAvailableException
 	 */
-	public function readAttribute($dn, $attr, $filter = 'objectClass=*') {
+	public function readAttribute(string $dn, string $attr, string $filter = 'objectClass=*') {
 		if (!$this->checkConnection()) {
 			\OCP\Util::writeLog('user_ldap',
 				'No LDAP Connector assigned, access impossible for readAttribute.',
@@ -203,6 +203,10 @@ public function readAttribute($dn, $attr, $filter = 'objectClass=*') {
 		// (cf. #12306), 500 is default for paging and should work everywhere.
 		$maxResults = $pagingSize > 20 ? $pagingSize : 500;
 		$attr = mb_strtolower($attr, 'UTF-8');
+		if ($attr === false) {
+			\OCP\Util::writeLog('user_ldap', 'Attribute name could not be converted to lower case.', ILogger::DEBUG);
+			return false;
+		}
 		// the actual read attribute later may contain parameters on a ranged
 		// request, e.g. member;range=99-199. Depends on server reply.
 		$attrToRead = $attr;
@@ -1759,6 +1763,7 @@ public function getUUID($dn, $isUser = true, $ldapRecord = null) {
 
 		$uuid = false;
 		if ($this->detectUuidAttribute($dn, $isUser, false, $ldapRecord)) {
+			/** @var string $attr */
 			$attr = $this->connection->$uuidAttr;
 			$uuid = isset($ldapRecord[$attr]) ? $ldapRecord[$attr] : $this->readAttribute($dn, $attr);
 			if (!is_array($uuid)
diff --git a/lib/private/AppFramework/Routing/RouteConfig.php b/lib/private/AppFramework/Routing/RouteConfig.php
index b382e7eb4b033..c522d3436cab8 100644
--- a/lib/private/AppFramework/Routing/RouteConfig.php
+++ b/lib/private/AppFramework/Routing/RouteConfig.php
@@ -231,7 +231,7 @@ protected function processResources(array $resources, string $routeNamePrefix =
 				$controllerName = $this->buildControllerName($controller);
 				$actionName = $this->buildActionName($method);
 
-				$routeName = $routeNamePrefix . $this->appName . '.' . strtolower($resource) . '.' . strtolower($method);
+				$routeName = $routeNamePrefix . $this->appName . '.' . strtolower($resource) . '.' . $method;
 
 				$route = $this->router->create($routeName, $url)
 					->method($verb);
diff --git a/lib/private/Setup.php b/lib/private/Setup.php
index 873e82e55de7f..990cc12bc9d15 100644
--- a/lib/private/Setup.php
+++ b/lib/private/Setup.php
@@ -187,13 +187,12 @@ public function getSupportedDatabases($allowAllDatabases = false) {
 
 		foreach ($configuredDatabases as $database) {
 			if (array_key_exists($database, $availableDatabases)) {
-				$working = false;
 				$type = $availableDatabases[$database]['type'];
 				$call = $availableDatabases[$database]['call'];
 
 				if ($type === 'function') {
 					$working = $this->is_callable($call);
-				} elseif ($type === 'pdo') {
+				} else {
 					$working = in_array($call, $this->getAvailableDbDriversForPdo(), true);
 				}
 				if ($working) {
diff --git a/lib/private/Share20/Manager.php b/lib/private/Share20/Manager.php
index 9a2b413896b00..4c3866d714e7c 100644
--- a/lib/private/Share20/Manager.php
+++ b/lib/private/Share20/Manager.php
@@ -1266,6 +1266,7 @@ public function getSharesBy($userId, $shareType, $path = null, $reshares = false
 			return [];
 		}
 
+		/** @var IShare[] $shares */
 		$shares = $provider->getSharesBy($userId, $shareType, $path, $reshares, $limit, $offset);
 
 		/*
@@ -1273,6 +1274,7 @@ public function getSharesBy($userId, $shareType, $path = null, $reshares = false
 		 * proper pagination.
 		 */
 
+		/** @var IShare[] $shares2 */
 		$shares2 = [];
 
 		while (true) {
diff --git a/lib/public/AppFramework/Db/QBMapper.php b/lib/public/AppFramework/Db/QBMapper.php
index 79b3701be2a3e..72373ba26c303 100644
--- a/lib/public/AppFramework/Db/QBMapper.php
+++ b/lib/public/AppFramework/Db/QBMapper.php
@@ -147,7 +147,9 @@ public function insert(Entity $entity): Entity {
 	 * updates an existing entry if duplicate keys are detected
 	 * by the database
 	 *
+	 * @param Entity $entity the entity that should be created/updated
 	 * @psalm-param T $entity the entity that should be created/updated
+	 * @return Entity the saved entity with the (new) id
 	 * @psalm-return T the saved entity with the (new) id
 	 * @throws \InvalidArgumentException if entity has no id
 	 * @since 15.0.0