diff --git a/core/js/setupchecks.js b/core/js/setupchecks.js
index cca3707acd..4aa60912c3 100644
--- a/core/js/setupchecks.js
+++ b/core/js/setupchecks.js
@@ -52,12 +52,16 @@
 		 * @param url the URL to test
 		 * @param placeholderUrl the placeholder URL - can be found at oc_defaults.docPlaceholderUrl
 		 * @param {boolean} runCheck if this is set to false the check is skipped and no error is returned
-		 * @param {int} expectedStatus the expected HTTP status to be returned by the URL, 207 by default
+		 * @param {int|int[]} expectedStatus the expected HTTP status to be returned by the URL, 207 by default
 		 * @return $.Deferred object resolved with an array of error messages
 		 */
 		checkWellKnownUrl: function(url, placeholderUrl, runCheck, expectedStatus) {
 			if (expectedStatus === undefined) {
-				expectedStatus = 207;
+				expectedStatus = [207];
+			}
+
+			if (!Array.isArray(expectedStatus)) {
+				expectedStatus = [expectedStatus];
 			}
 
 			var deferred = $.Deferred();
@@ -68,7 +72,7 @@
 			}
 			var afterCall = function(xhr) {
 				var messages = [];
-				if (xhr.status !== expectedStatus) {
+				if (expectedStatus.indexOf(xhr.status) === -1) {
 					var docUrl = placeholderUrl.replace('PLACEHOLDER', 'admin-setup-well-known-URL');
 					messages.push({
 						msg: t('core', 'Your web server is not properly set up to resolve "{url}". Further information can be found in the <a target="_blank" rel="noreferrer noopener" href="{docLink}">documentation</a>.', { docLink: docUrl, url: url }),
diff --git a/public.php b/public.php
index f033e1897c..ae95624e8d 100644
--- a/public.php
+++ b/public.php
@@ -68,7 +68,8 @@ try {
 	OC_App::loadApps(array('filesystem', 'logging'));
 
 	if (!\OC::$server->getAppManager()->isInstalled($app)) {
-		throw new Exception('App not installed: ' . $app);
+		http_response_code(501);
+		exit;
 	}
 	OC_App::loadApp($app);
 	OC_User::setIncognitoMode(true);
diff --git a/settings/js/admin.js b/settings/js/admin.js
index 2f3cc0356c..8c198bc782 100644
--- a/settings/js/admin.js
+++ b/settings/js/admin.js
@@ -247,7 +247,7 @@ $(document).ready(function(){
 	// run setup checks then gather error messages
 	$.when(
 		OC.SetupChecks.checkWebDAV(),
-		OC.SetupChecks.checkWellKnownUrl('/.well-known/webfinger', oc_defaults.docPlaceholderUrl, $('#postsetupchecks').data('check-wellknown') === true && !!oc_appconfig.core.public_webfinger, 200),
+		OC.SetupChecks.checkWellKnownUrl('/.well-known/webfinger', oc_defaults.docPlaceholderUrl, $('#postsetupchecks').data('check-wellknown') === true && !!oc_appconfig.core.public_webfinger, [200, 501]),
 		OC.SetupChecks.checkWellKnownUrl('/.well-known/caldav', oc_defaults.docPlaceholderUrl, $('#postsetupchecks').data('check-wellknown') === true),
 		OC.SetupChecks.checkWellKnownUrl('/.well-known/carddav', oc_defaults.docPlaceholderUrl, $('#postsetupchecks').data('check-wellknown') === true),
 		OC.SetupChecks.checkSetup(),