Datei oder Ordner nicht gefunden

Nextcloud version: 18.0.3
Operating system and version (eg, Ubuntu 20.04): ?
Apache or nginx version (eg, Apache 2.4.25): ?
PHP version (eg, 7.1): 7.4.6
mysql Version: 5.6.42

The issue you are facing: Bei der Synchronisierung beim Nextcloud-Client unter Windows 10 erhalte ich die Fehlermeldung: Datei oder Ordner nicht gefunden: [Ordnername]. Ich kann den Ordner auch nicht im Browserverzeichnis löschen, da ich dort die Meldung erhalte, dass der Ordner (richtigerweise) nicht existiert. Was kann ich machen, damit solche Synchronisierungsprobleme nicht auftreten? Über die Suche habe ich leider nichts finden können. Ich habe Nextcloud nur installiert und nichts verändert/editiert.

Is this the first time you’ve seen this error? (Y/N): Y

The output of your Nextcloud log in Admin > Logging:

Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:39:06+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:38:44+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/Os.php#155	
2020-06-11T17:38:44+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T17:38:44+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/templates/settings-admin.php#101	
2020-06-11T17:38:43+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T17:38:43+0200
Error	PHP	A non-numeric value encountered at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#52	
2020-06-11T17:38:43+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:35:12+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/Os.php#155	
2020-06-11T17:34:24+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T17:34:24+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:34:24+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/templates/settings-admin.php#101	
2020-06-11T17:34:23+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T17:34:22+0200
Error	PHP	A non-numeric value encountered at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#52	
2020-06-11T17:34:22+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:33:59+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:25:37+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/Os.php#155	
2020-06-11T17:25:16+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T17:25:16+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:25:16+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/templates/settings-admin.php#101	
2020-06-11T17:25:15+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T17:25:14+0200
Error	PHP	A non-numeric value encountered at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#52	
2020-06-11T17:25:14+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:25:10+0200
Error	PHP	Trying to access array offset on value of type bool at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/settings/lib/Settings/Admin/Server.php#55	
2020-06-11T17:25:08+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:22:43+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T17:22:37+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T16:57:27+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T16:51:23+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: Expected filesize of 2247344 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:33:31+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: Expected filesize of 2247344 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:33:31+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: Expected filesize of 1908259 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:32:40+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: Expected filesize of 1908259 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:32:40+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: Expected filesize of 2302977 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:30:53+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: Expected filesize of 2302977 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:30:53+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/Os.php#155	
2020-06-11T08:29:55+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T08:29:55+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T08:29:55+0200
Error	PHP	Invalid argument supplied for foreach() at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/templates/settings-admin.php#101	
2020-06-11T08:29:54+0200
Error	PHP	Undefined variable: result at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#173	
2020-06-11T08:29:52+0200
Error	PHP	A non-numeric value encountered at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/apps/serverinfo/lib/OperatingSystems/DefaultOs.php#52	
2020-06-11T08:29:52+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T08:29:45+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: Expected filesize of 2004502 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:24:13+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: Expected filesize of 2004502 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:24:13+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: Expected filesize of 1852204 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:22:33+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: Expected filesize of 1852204 bytes but read (from Nextcloud client) and wrote (to Nextcloud storage) 8192 bytes. Could either be a network problem on the sending side or a problem writing to the storage on the server side.	
2020-06-11T08:22:33+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T08:18:13+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:17:40+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T08:17:15+0200
Warning	core	Login failed: *** (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:17:15+0200
Warning	core	Login failed: *** (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:16:50+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:16:24+0200
Warning	core	Login failed: *** (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:15:59+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T08:01:07+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:01:07+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:00:42+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T08:00:17+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:59:51+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:59:26+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:58:35+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:58:34+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:58:09+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-11T07:58:08+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:58:08+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:58:01+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:58:00+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:57:59+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:57:58+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:57:56+0200
Warning	core	Login failed: '***' (Remote IP: '2001:16b8:2d0c:a500:1934:384e:d0d8:eb60')	
2020-06-11T07:57:55+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-06T19:49:33+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-06T19:48:32+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-06T19:48:05+0200
Error	PHP	opendir(/var/tmp/): failed to open dir: Permission denied at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/TempManager.php#190	
2020-06-06T19:39:49+0200
Error	PHP	Out of memory (allocated 167772160) (tried to allocate 12288 bytes) at /mnt/web010/d2/87/5843287/htdocs/sites/***/next/lib/private/legacy/image.php#879	
2020-05-11T21:42:43+0200

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

<?php
$CONFIG = array (
  'instanceid' => '***',
  'passwordsalt' => '***',
  'secret' => '***',
  'trusted_domains' => 
  array (
    0 => '***',
  ),
  'datadirectory' => '/mnt/web010/d2/87/5843287/htdocs/sites/***/next/data',
  'dbtype' => 'mysql',
  'version' => '18.0.3.0',
  'overwrite.cli.url' => '***',
  'dbname' => '***',
  'dbhost' => 'rdbms.strato.de',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '***',
  'dbpassword' => '***',
  'installed' => true,
);

The output of your Apache/nginx/system log in /var/log/____:

?