TYPO3 Core

I have about 10 such entries per day in the log:

Sat, 26 Feb 2022 17:37:27 +0100 [WARNING] request="a2ab16ea9d6ba" component="TYPO3.CMS.Core.Error.ErrorHandler": Core: Error handler (FE): PHP Warning: filemtime(): stat failed for /www/htdocs/typo3temp/var/session/965e817f98876f860f9b3fd9c6b522f0aa9aaf6d/hash_c845ed11a7dc29cfab61d133e4aaf948 in /www/htdocs/typo3_src-10.4.25/typo3/sysext/install/Classes/Service/Session/FileSessionHandler.php line 204

File FileSessionHandler.php:

196     public function gc($maxLifeTime)
197     {
198         $sessionSavePath = $this->getSessionSavePath();
199         $files = glob($sessionSavePath . '/hash_*');
200         if (!is_array($files)) {
201             return true;
202         }
203         foreach ($files as $filename) {
204             if (filemtime($filename) + $this->expirationTimeInMinutes * 60 < time()) {
205                 @unlink($filename);
206             }
207         }
208         return true;
209     }

However, the function has a very simple structure. Glob searches for the files, which are then deleted in a foreach loop. I don't understand how files are found here that are no longer available shortly afterwards.

(First of all no problem, the argument $maxLifeTime is not used within the function.)

I have been using this typo3 installation for years without any errors. Unfortunately I don't know the exact time since the problem started. Probably typo3 versions 10.4.21 - 10.4.23. Version 10.4.25 is currently in use with PHP 7.4.3 (fpm/Apache) on Ubuntu-Server 20.04.4.

The directory exists, there are also session files:

$ ls -l /www/htdocs/typo3temp/var/session/965e817f98876f860f9b3fd9c6b522f0aa9aaf6d
total 592K
drwxrwsr-x 2 www-user www-user  48K Feb 28 12:50 .
drwxrwsr-x 3 www-user www-user 4,0K Jan 27 14:02 ..
-rw-rw-r-- 1 www-user www-user   11 Feb 28 12:40 hash_031a442747c706b9e92087b3097e8cb0
-rw-rw-r-- 1 www-user www-user  10K Feb 28 12:36 hash_03db333aa9563b4ee7ccb225d5000a75
-rw-rw-r-- 1 www-user www-user   11 Feb 28 12:36 hash_068c1cbd2ff5873af4da2d695338664f
-rw-rw-r-- 1 www-user www-user  10K Feb 28 12:40 hash_09ded894bea3b1d9d9373b0814f68321
-rw-rw-r-- 1 www-user www-user  10K Feb 28 12:40 hash_0d0e1f6329f1fee0c175b87c882f161f
-rw-rw-r-- 1 www-user www-user  10K Feb 28 12:44 hash_0d77a82d9e26d49a95cc1cfb0e920d40

According to github, there hasn't been any change to this gc() function for a long time.

https://github.com/TYPO3/typo3/commits/main/typo3/sysext/install/Classes/Service/Session/FileSessionHandler.php

Now I have no more ideas. Maybe a php problem? The Ext4 file system has been checked and is ok.

Thanks.