NextCloud throws a PHP-Script-Error a few times a day

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Nextcloud version (eg, 10.0.2): 11.0.3
Operating system and version (eg, Ubuntu 16.04): Ubuntu-Server 16.04 LTS
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.18
PHP version (eg, 5.6): 7.0.15
Is this the first time you’ve seen this error?: No, it is not the first time, it happened a few times this week…

Can you reliably replicate it? (If so, please outline steps): No, I am not able to replicate it, it is a temporarily error, that happens a few times a day.

The issue you are facing:
My NextCloud-Instance throws this PHP-Error a few times a day

The output of your Nextcloud log in Admin > Logging:

Error PHP
Uncaught Error: Access to undeclared static property: OC\Files\Filesystem::$normalizedPathCache in /var/www/nextcloud/lib/private/Files/Filesystem.php:806 Stack trace: #0 /var/www/nextcloud/lib/private/Files/View.php(2018): OC\Files\Filesystem::normalizePath(’/xxxxxx/files/…’) #1 /var/www/nextcloud/lib/private/Files/View.php(1156): OC\Files\View->unlockFile(’/xxxxxxxxx’, 1) #2 [internal function]: OC\Files\View->OC\Files{closure}() #3 /var/www/nextcloud/3rdparty/icewind/streams/src/CallbackWrapper.php(109): call_user_func(Object(Closure)) #4 [internal function]: Icewind\Streams\CallbackWrapper->stream_close() #5 {main} thrown at /var/www/nextcloud/lib/private/Files/Filesystem.php#806

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php $CONFIG = array ( 'instanceid' => 'xxxxx', 'passwordsalt' => 'xxxxxxx', 'secret' => 'xxxxxxxxxx', 'trusted_domains' => array ( 0 => 'xxxxxx', 1 => 'xxxxxxx', 2 => 'xxxxxxxx', 3 => 'xxxxxxxxxx', ), 'datadirectory' => '/backup/data', 'overwrite.cli.url' => 'https://xxxxxxxxxxxx/owncloud', 'dbtype' => 'mysql', 'version' => '', 'dbname' => 'xxxxxxxxxx', 'dbhost' => 'xxxxxxxxxxxx', 'dbtableprefix' => 'oc_', 'dbuser' => 'owncloud', 'dbpassword' => 'xxxxxxxxxxxx', 'logtimezone' => 'UTC', 'installed' => true, 'loglevel' => 2, 'mail_smtpmode' => 'smtp', 'mail_from_address' => 'xxxxxxxxx', 'mail_domain' => 'xxxxxxxxxx', 'mail_smtphost' => '', 'mail_smtpport' => '25', 'theme' => '', 'maintenance' => false, 'memcache.local' => '\OC\Memcache\APCu', ); The output of your Apache/nginx/system log in /var/log/____: [Tue Apr 25 07:33:13.618765 2017] [ssl:warn] [pid 3035] AH01909: server certificate does NOT include an ID which matches the server name [Tue Apr 25 07:33:13.618958 2017] [mpm_prefork:notice] [pid 3035] AH00163: Apache/2.4.18 (Ubuntu) OpenSSL/1.0.2g configured -- resuming normal operations [Tue Apr 25 07:33:13.618968 2017] [core:notice] [pid 3035] AH00094: Command line: '/usr/sbin/apache2' [Tue Apr 25 07:59:48.910099 2017] [:error] [pid 3962] [clientxxxxxxxx] PHP Fatal error: Uncaught Error: Access to undeclared static property: OC\\Files\\Filesystem::$normalizedPathCache in /var/www/nextcloud/lib/private/Files/Filesystem.php:806\nStack trace:\n#0 /var/www/nextcloud/lib/private/Files/View.php(2018): OC\\Files\\Filesystem::normalizePath('/benedikt/files...')\n#1 /var/www/nextcloud/lib/private/Files/View.php(1156): OC\\Files\\View->unlockFile('/!Marketing Hir...', 1)\n#2 [internal function]: OC\\Files\\View->OC\\Files\\{closure}()\n#3 /var/www/nextcloud/3rdparty/icewind/streams/src/CallbackWrapper.php(109): call_user_func(Object(Closure))\n#4 [internal function]: Icewind\\Streams\\CallbackWrapper->stream_close()\n#5 {main}\n thrown in /var/www/nextcloud/lib/private/Files/Filesystem.php on line 806