diff --git a/apps/files/lib/Helper.php b/apps/files/lib/Helper.php
index 67e2fbe8321dc..18fea3aa2a11f 100644
--- a/apps/files/lib/Helper.php
+++ b/apps/files/lib/Helper.php
@@ -216,7 +216,7 @@ public static function getFiles($dir, $sortAttribute = 'name', $sortDescending =
 	 * @param ITagManager $tagManager
 	 * @return array file list populated with tags
 	 */
-	public static function populateTags(array $fileList, $fileIdentifier = 'fileid', ITagManager $tagManager) {
+	public static function populateTags(array $fileList, $fileIdentifier, ITagManager $tagManager) {
 		$ids = [];
 		foreach ($fileList as $fileData) {
 			$ids[] = $fileData[$fileIdentifier];
diff --git a/core/Controller/PreviewController.php b/core/Controller/PreviewController.php
index e1bfa01b238a6..1224ea39877b3 100644
--- a/core/Controller/PreviewController.php
+++ b/core/Controller/PreviewController.php
@@ -155,8 +155,8 @@ private function fetchPreview(
 		Node $node,
 		int $x,
 		int $y,
-		bool $a = false,
-		bool $forceIcon = true,
+		bool $a,
+		bool $forceIcon,
 		string $mode) : Http\Response {
 		if (!($node instanceof File) || (!$forceIcon && !$this->preview->isAvailable($node))) {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
diff --git a/lib/private/Files/Config/CachedMountFileInfo.php b/lib/private/Files/Config/CachedMountFileInfo.php
index a179b9aef8bc8..7fdc26f7d5345 100644
--- a/lib/private/Files/Config/CachedMountFileInfo.php
+++ b/lib/private/Files/Config/CachedMountFileInfo.php
@@ -30,7 +30,7 @@ class CachedMountFileInfo extends CachedMountInfo implements ICachedMountFileInf
 	/** @var string */
 	private $internalPath;
 
-	public function __construct(IUser $user, $storageId, $rootId, $mountPoint, $mountId = null, $rootInternalPath = '', $internalPath) {
+	public function __construct(IUser $user, $storageId, $rootId, $mountPoint, $mountId, $rootInternalPath, $internalPath) {
 		parent::__construct($user, $storageId, $rootId, $mountPoint, $mountId, $rootInternalPath);
 		$this->internalPath = $internalPath;
 	}
diff --git a/lib/private/Files/View.php b/lib/private/Files/View.php
index e11b9be9fed12..113290e2686fb 100644
--- a/lib/private/Files/View.php
+++ b/lib/private/Files/View.php
@@ -421,7 +421,9 @@ public function filesize($path) {
 	 */
 	public function readfile($path) {
 		$this->assertPathLength($path);
-		@ob_end_clean();
+		if (ob_get_level()) {
+			ob_end_clean();
+		}
 		$handle = $this->fopen($path, 'rb');
 		if ($handle) {
 			$chunkSize = 524288; // 512 kB chunks
@@ -445,7 +447,9 @@ public function readfile($path) {
 	 */
 	public function readfilePart($path, $from, $to) {
 		$this->assertPathLength($path);
-		@ob_end_clean();
+		if (ob_get_level()) {
+			ob_end_clean();
+		}
 		$handle = $this->fopen($path, 'rb');
 		if ($handle) {
 			$chunkSize = 524288; // 512 kB chunks
diff --git a/lib/public/AppFramework/Http/Template/PublicTemplateResponse.php b/lib/public/AppFramework/Http/Template/PublicTemplateResponse.php
index 70bec65b096dc..1196c90935dd0 100644
--- a/lib/public/AppFramework/Http/Template/PublicTemplateResponse.php
+++ b/lib/public/AppFramework/Http/Template/PublicTemplateResponse.php
@@ -96,7 +96,7 @@ public function setHeaderActions(array $actions) {
 			$this->headerActions[] = $action;
 		}
 		usort($this->headerActions, function (IMenuAction $a, IMenuAction $b) {
-			return $a->getPriority() > $b->getPriority();
+			return $a->getPriority() <=> $b->getPriority();
 		});
 	}