diff --git a/apps/workflowengine/lib/Entity/File.php b/apps/workflowengine/lib/Entity/File.php
index 9131caf888a7a..e780f82d08ef5 100644
--- a/apps/workflowengine/lib/Entity/File.php
+++ b/apps/workflowengine/lib/Entity/File.php
@@ -140,7 +140,7 @@ public function isLegitimatedForUserId(string $uid): bool {
 				return true;
 			}
 			$acl = $this->shareManager->getAccessList($node, true, true);
-			return array_key_exists($uid, $acl['users']);
+			return isset($acl['users']) && array_key_exists($uid, $acl['users']);
 		} catch (NotFoundException $e) {
 			return false;
 		}