diff --git a/lib/Controller/SAMLController.php b/lib/Controller/SAMLController.php
index e2b58838e..e42c51dd4 100644
--- a/lib/Controller/SAMLController.php
+++ b/lib/Controller/SAMLController.php
@@ -539,7 +539,7 @@ public function genericError(string $message): Http\TemplateResponse {
 	 * @NoCSRFRequired
 	 * @OnlyUnauthenticatedUsers
 	 */
-	public function selectUserBackEnd(string $redirectUrl): Http\TemplateResponse {
+	public function selectUserBackEnd(string $redirectUrl = ''): Http\TemplateResponse {
 		$attributes = ['loginUrls' => []];
 
 		if ($this->samlSettings->allowMultipleUserBackEnds()) {