diff --git a/lib/private/AppConfig.php b/lib/private/AppConfig.php
index 85b5b402e4b..4702b47f405 100644
--- a/lib/private/AppConfig.php
+++ b/lib/private/AppConfig.php
@@ -840,8 +840,12 @@ class AppConfig implements IAppConfig {
 				$type |= self::VALUE_SENSITIVE;
 			}
 
-			if ($lazy !== $this->isLazy($app, $key)) {
-				$refreshCache = true;
+			try {
+				if ($lazy !== $this->isLazy($app, $key)) {
+					$refreshCache = true;
+				}
+			} catch (AppConfigUnknownKeyException) {
+				// pass
 			}
 
 			$update = $this->connection->getQueryBuilder();