diff --git a/lib/private/Route/Router.php b/lib/private/Route/Router.php
index 71bc4a6c4f7d8..9f592bcb674c9 100644
--- a/lib/private/Route/Router.php
+++ b/lib/private/Route/Router.php
@@ -131,8 +131,9 @@ public function loadRoutes($app = null) {
 			if (isset($this->loadedApps[$app])) {
 				return;
 			}
-			$file = \OC_App::getAppPath($app) . '/appinfo/routes.php';
-			if ($file !== false && file_exists($file)) {
+			$appPath = \OC_App::getAppPath($app);
+			$file = $appPath . '/appinfo/routes.php';
+			if ($appPath !== false && file_exists($file)) {
 				$routingFiles = [$app => $file];
 			} else {
 				$routingFiles = [];
diff --git a/lib/private/Template/Base.php b/lib/private/Template/Base.php
index 65d0ad469ff3d..a42ddccbc0007 100644
--- a/lib/private/Template/Base.php
+++ b/lib/private/Template/Base.php
@@ -65,7 +65,7 @@ public function __construct($template, $requestToken, $l10n, $theme) {
 	 */
 	protected function getAppTemplateDirs($theme, $app, $serverRoot, $app_dir) {
 		// Check if the app is in the app folder or in the root
-		if (file_exists($app_dir.'/templates/')) {
+		if ($app_dir !== false && file_exists($app_dir.'/templates/')) {
 			return [
 				$serverRoot.'/themes/'.$theme.'/apps/'.$app.'/templates/',
 				$app_dir.'/templates/',
diff --git a/lib/private/Template/IconsCacher.php b/lib/private/Template/IconsCacher.php
index 9b80711dd2940..a3318c61d4747 100644
--- a/lib/private/Template/IconsCacher.php
+++ b/lib/private/Template/IconsCacher.php
@@ -171,7 +171,10 @@ private function parseUrl($url): array {
 		} elseif (\strpos($url, $base) === 0) {
 			if (\preg_match('/([A-z0-9\_\-]+)\/([a-zA-Z0-9-_\~\/\.\=\:\;\+\,]+)\?color=([0-9a-fA-F]{3,6})/', $cleanUrl, $matches)) {
 				list(,$app,$cleanUrl, $color) = $matches;
-				$location = \OC_App::getAppPath($app) . '/img/' . $cleanUrl . '.svg';
+				$appPath = \OC_App::getAppPath($app);
+				if ($appPath !== false) {
+					$location = $appPath . '/img/' . $cleanUrl . '.svg';
+				}
 				if ($app === 'settings') {
 					$location = \OC::$SERVERROOT . '/settings/img/' . $cleanUrl . '.svg';
 				}
diff --git a/lib/private/Template/ResourceLocator.php b/lib/private/Template/ResourceLocator.php
index 1d9f60cf5dd38..a6f9f63ef7ddb 100755
--- a/lib/private/Template/ResourceLocator.php
+++ b/lib/private/Template/ResourceLocator.php
@@ -103,7 +103,7 @@ public function find($resources) {
 	 * @return bool True if the resource was found, false otherwise
 	 */
 	protected function appendIfExist($root, $file, $webRoot = null) {
-		if (is_file($root.'/'.$file)) {
+		if ($root !== false && is_file($root.'/'.$file)) {
 			$this->append($root, $file, $webRoot, false);
 			return true;
 		}