diff --git a/lib/Middleware/ExAppUIL10NMiddleware.php b/lib/Middleware/ExAppUIL10NMiddleware.php
index 09a6a84b2..5f69a983b 100644
--- a/lib/Middleware/ExAppUIL10NMiddleware.php
+++ b/lib/Middleware/ExAppUIL10NMiddleware.php
@@ -38,7 +38,7 @@ public function __construct(
 	) {
 	}
 
-	public function beforeOutput(Controller $controller, string $methodName, string $output) {
+	public function beforeOutput(Controller $controller, string $methodName, string $output): string {
 		$url = $this->request->getRequestUri();
 		$loadL10N = false;
 		foreach (self::routesToLoadL10N as $route) {
diff --git a/lib/Middleware/ExAppUiMiddleware.php b/lib/Middleware/ExAppUiMiddleware.php
index 158a8c0cc..9964e488b 100644
--- a/lib/Middleware/ExAppUiMiddleware.php
+++ b/lib/Middleware/ExAppUiMiddleware.php
@@ -26,14 +26,14 @@ public function __construct(
 	) {
 	}
 
-	public function beforeOutput(Controller $controller, string $methodName, string $output) {
+	public function beforeOutput(Controller $controller, string $methodName, string $output): string {
 		if (($controller instanceof TopMenuController) && ($controller->postprocess)) {
-			$output = preg_replace(
+			$output = (string)preg_replace(
 				'/(href=")(\/.*?)(\/app_api\/css\/)(proxy\/.*css.*")/',
 				'$1/index.php/apps/app_api/$4',
 				$output);
 			foreach ($controller->jsProxyMap as $key => $value) {
-				$output = preg_replace(
+				$output = (string)preg_replace(
 					'/(src=")(\/.*?)(\/app_api\/js\/)(proxy_js\/' . (string)$key . '.js)(.*")/',
 					'$1/index.php/apps/app_api/proxy/' . $value . '.js$5',
 					$output,
@@ -43,7 +43,7 @@ public function beforeOutput(Controller $controller, string $methodName, string
 		return $output;
 	}
 
-	public function afterController(Controller $controller, string $methodName, Response $response) {
+	public function afterController(Controller $controller, string $methodName, Response $response): Response {
 		if (($controller instanceof TopMenuController) && ($controller->postprocess)) {
 			$exAppId = $this->request->getParam('appId');
 			$menuEntryName = $this->request->getParam('name');
diff --git a/lib/Migration/Version2000Date20240120094952.php b/lib/Migration/Version2000Date20240120094952.php
index bcc7badec..410877276 100644
--- a/lib/Migration/Version2000Date20240120094952.php
+++ b/lib/Migration/Version2000Date20240120094952.php
@@ -37,7 +37,7 @@ public function changeSchema(IOutput $output, Closure $schemaClosure, array $opt
 		$table->addUniqueIndex(['daemon_config_name', 'port'], 'ex_apps_c_port__idx');
 
 		$table = $schema->getTable('ex_apps_daemons');
-		$table->changeColumn('deploy_config', [
+		$table->modifyColumn('deploy_config', [
 			'notnull' => true,
 		]);
 
diff --git a/lib/Service/ExAppOccService.php b/lib/Service/ExAppOccService.php
index d982b871b..6f54cb8d7 100644
--- a/lib/Service/ExAppOccService.php
+++ b/lib/Service/ExAppOccService.php
@@ -128,7 +128,7 @@ public function __construct(
 				$this->service = $this->container->get(PublicFunctions::class);
 			}
 
-			protected function configure() {
+			protected function configure(): void {
 				$this->setName($this->occCommand->getName());
 				$this->setDescription($this->occCommand->getDescription());
 				$this->setHidden(filter_var($this->occCommand->getHidden(), FILTER_VALIDATE_BOOLEAN));
diff --git a/tests/psalm-baseline.xml b/tests/psalm-baseline.xml
index 1eb3124bb..e85149ee7 100644
--- a/tests/psalm-baseline.xml
+++ b/tests/psalm-baseline.xml
@@ -142,14 +142,6 @@
       <code><![CDATA[IEventListener]]></code>
     </MissingTemplateParam>
   </file>
-  <file src="lib/Middleware/ExAppUiMiddleware.php">
-    <InvalidNullableReturnType>
-      <code><![CDATA[beforeOutput]]></code>
-    </InvalidNullableReturnType>
-    <NullableReturnStatement>
-      <code><![CDATA[$output]]></code>
-    </NullableReturnStatement>
-  </file>
   <file src="lib/Service/ExAppOccService.php">
     <InvalidReturnStatement>
       <code><![CDATA[new class($occCommand, $container) extends Command {