diff --git a/lib/Middleware/SessionMiddleware.php b/lib/Middleware/SessionMiddleware.php
index 6697dc544d4..e72646e404d 100644
--- a/lib/Middleware/SessionMiddleware.php
+++ b/lib/Middleware/SessionMiddleware.php
@@ -143,7 +143,7 @@ private function assertUserOrShareToken(ISessionAwareController $controller): vo
 
 	public function afterException($controller, $methodName, \Exception $exception): JSONResponse|Response {
 		if ($exception instanceof InvalidDocumentBaseVersionEtagException) {
-			return new JSONResponse($this->l10n->t('Editing session has expired. Please reload the page.'), Http::STATUS_PRECONDITION_FAILED);
+			return new JSONResponse(['error' => $this->l10n->t('Editing session has expired. Please reload the page.')], Http::STATUS_PRECONDITION_FAILED);
 		}
 
 		if ($exception instanceof InvalidSessionException) {
diff --git a/lib/Service/ApiService.php b/lib/Service/ApiService.php
index 1be3bf51d97..488b6986db0 100644
--- a/lib/Service/ApiService.php
+++ b/lib/Service/ApiService.php
@@ -85,17 +85,17 @@ public function create(?int $fileId = null, ?string $filePath = null, ?string $b
 				} catch (NotFoundException $e) {
 					return new DataResponse([], Http::STATUS_NOT_FOUND);
 				} catch (NotPermittedException $e) {
-					return new DataResponse($this->l10n->t('This file cannot be displayed as download is disabled by the share'), 404);
+					return new DataResponse(['error' => $this->l10n->t('This file cannot be displayed as download is disabled by the share')], 404);
 				}
 			} elseif ($fileId) {
 				try {
 					$file = $this->documentService->getFileById($fileId);
 				} catch (NotFoundException|NotPermittedException $e) {
 					$this->logger->error('No permission to access this file', [ 'exception' => $e ]);
-					return new DataResponse($this->l10n->t('No permission to access this file.'), Http::STATUS_NOT_FOUND);
+					return new DataResponse(['error' => $this->l10n->t('No permission to access this file.')], Http::STATUS_NOT_FOUND);
 				}
 			} else {
-				return new DataResponse('No valid file argument provided', Http::STATUS_PRECONDITION_FAILED);
+				return new DataResponse(['error' => 'No valid file argument provided'], Http::STATUS_PRECONDITION_FAILED);
 			}
 
 			$storage = $file->getStorage();
@@ -106,7 +106,7 @@ public function create(?int $fileId = null, ?string $filePath = null, ?string $b
 				$share = $storage->getShare();
 				$shareAttribtues = $share->getAttributes();
 				if ($shareAttribtues !== null && $shareAttribtues->getAttribute('permissions', 'download') === false) {
-					return new DataResponse($this->l10n->t('This file cannot be displayed as download is disabled by the share'), 403);
+					return new DataResponse(['error' => $this->l10n->t('This file cannot be displayed as download is disabled by the share')], 403);
 				}
 			}
 
@@ -116,7 +116,7 @@ public function create(?int $fileId = null, ?string $filePath = null, ?string $b
 			$document = $this->documentService->getDocument($file->getId());
 			$freshSession = $document === null;
 			if ($baseVersionEtag && $baseVersionEtag !== $document?->getBaseVersionEtag()) {
-				return new DataResponse($this->l10n->t('Editing session has expired. Please reload the page.'), Http::STATUS_PRECONDITION_FAILED);
+				return new DataResponse(['error' => $this->l10n->t('Editing session has expired. Please reload the page.')], Http::STATUS_PRECONDITION_FAILED);
 			}
 
 			if ($freshSession) {
@@ -132,7 +132,7 @@ public function create(?int $fileId = null, ?string $filePath = null, ?string $b
 			}
 		} catch (Exception $e) {
 			$this->logger->error($e->getMessage(), ['exception' => $e]);
-			return new DataResponse('Failed to create the document session', 500);
+			return new DataResponse(['error' => 'Failed to create the document session'], 500);
 		}
 
 		/** @var Document $document */
@@ -193,7 +193,7 @@ public function push(Session $session, Document $document, int $version, array $
 			$session = $this->sessionService->updateSessionAwareness($session, $awareness);
 		} catch (DoesNotExistException $e) {
 			// Session was removed in the meantime. #3875
-			return new DataResponse($this->l10n->t('Editing session has expired. Please reload the page.'), Http::STATUS_PRECONDITION_FAILED);
+			return new DataResponse(['error' => $this->l10n->t('Editing session has expired. Please reload the page.')], Http::STATUS_PRECONDITION_FAILED);
 		}
 		if (empty($steps)) {
 			return new DataResponse([]);
@@ -201,10 +201,10 @@ public function push(Session $session, Document $document, int $version, array $
 		try {
 			$result = $this->documentService->addStep($document, $session, $steps, $version, $token);
 		} catch (InvalidArgumentException $e) {
-			return new DataResponse($e->getMessage(), 422);
+			return new DataResponse(['error' => $e->getMessage()], 422);
 		} catch (DoesNotExistException|NotPermittedException) {
 			// Either no write access or session was removed in the meantime (#3875).
-			return new DataResponse($this->l10n->t('Editing session has expired. Please reload the page.'), Http::STATUS_PRECONDITION_FAILED);
+			return new DataResponse(['error' => $this->l10n->t('Editing session has expired. Please reload the page.')], Http::STATUS_PRECONDITION_FAILED);
 		}
 		return new DataResponse($result);
 	}
diff --git a/src/components/Editor/DocumentStatus.vue b/src/components/Editor/DocumentStatus.vue
index 014ac7a25ee..0061099826c 100644
--- a/src/components/Editor/DocumentStatus.vue
+++ b/src/components/Editor/DocumentStatus.vue
@@ -24,7 +24,7 @@
 	<div class="document-status">
 		<NcNoteCard v-if="hasWarning" type="warning">
 			<p v-if="isLoadingError">
-				{{ syncError.data.data }}
+				{{ syncError.data.data.error }}
 				<!-- Display reload button on PRECONDITION_FAILED response type -->
 				<a v-if="syncError.data.status === 412" class="button primary" @click="reload">{{ t('text', 'Reload') }}</a>
 			</p>