Nextcloud is not avaliable anymore due to error level 4

Hello,

today I recognized, that I cannot aces my nextcloud server anymore. This is the case from outside the local network and from inside. I can aces other services (subsonic) without any problems.
The server is running since the beginning of this year without any problems. In the nextcloud log there are level 3 and 4 errors listet due to movements of files while syncinc as far as I understood. Can anybody tell me how to get this solved?

Edit:
sudo -u www-data php /var/www/html/nextcloud/occ status

leads to:

  - installed: true
  - version: 15.0.2.0
  - versionstring: 15.0.2
  - edition: 

Thank you very much!

Nextcloud version 15.0.2
Operating system and version Ubuntu 18.04.3 LTS
Apache or nginx version Apache/2.4.29
PHP version 7.2.19

The last 5 lines output of Nextcloud log in Admin > Logging:

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{"reqId":"4IFXgEPlq9hcyQQBv66I","level":3,"time":"2019-10-12T07:00:10+00:00","remoteAddr":"192.168.2.1","user":"gerwern","app":"no app in context","method":"PUT","url":"\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","message":{"Exception":"Sabre\\DAV\\Exception\\BadRequest","Message":"expected filesize 23333079 got 16334848","Code":0,"Trace":[{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Connector\/Sabre\/Directory.php","line":156,"function":"put","class":"OCA\\DAV\\Connector\\Sabre\\File","type":"->","args":[null]},{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Upload\/UploadFolder.php","line":39,"function":"createFile","class":"OCA\\DAV\\Connector\\Sabre\\Directory","type":"->","args":["00000004",null]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","line":1096,"function":"createFile","class":"OCA\\DAV\\Upload\\UploadFolder","type":"->","args":["00000004",null]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/CorePlugin.php","line":525,"function":"createFile","class":"Sabre\\DAV\\Server","type":"->","args":["uploads\/gerwern\/60407603\/00000004",null,null]},{"function":"httpPut","class":"Sabre\\DAV\\CorePlugin","type":"->","args":[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php","line":105,"function":"call_user_func_array","args":[[{"__class__":"Sabre\\DAV\\CorePlugin"},"httpPut"],[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","line":479,"function":"emit","class":"Sabre\\Event\\EventEmitter","type":"->","args":["method:PUT",[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","line":254,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->","args":[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Server.php","line":301,"function":"exec","class":"Sabre\\DAV\\Server","type":"->","args":[]},{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/appinfo\/v2\/remote.php","line":35,"function":"exec","class":"OCA\\DAV\\Server","type":"->","args":[]},{"file":"\/var\/www\/html\/nextcloud\/remote.php","line":163,"args":["\/var\/www\/html\/nextcloud\/apps\/dav\/appinfo\/v2\/remote.php"],"function":"require_once"}],"File":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Connector\/Sabre\/File.php","Line":200,"CustomMessage":"--"},"userAgent":"Mozilla\/5.0 (Windows) mirall\/2.6.0stable-Win64 (build 20190927) (Nextcloud)","version":"15.0.2.0"}
{"reqId":"4IFXgEPlq9hcyQQBv66I","level":4,"time":"2019-10-12T07:00:10+00:00","remoteAddr":"192.168.2.1","user":"gerwern","app":"webdav","method":"PUT","url":"\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","message":{"Exception":"Sabre\\DAV\\Exception\\BadRequest","Message":"expected filesize 23333079 got 16334848","Code":0,"Trace":[{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Connector\/Sabre\/Directory.php","line":156,"function":"put","class":"OCA\\DAV\\Connector\\Sabre\\File","type":"->","args":[null]},{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Upload\/UploadFolder.php","line":39,"function":"createFile","class":"OCA\\DAV\\Connector\\Sabre\\Directory","type":"->","args":["00000004",null]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","line":1096,"function":"createFile","class":"OCA\\DAV\\Upload\\UploadFolder","type":"->","args":["00000004",null]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/CorePlugin.php","line":525,"function":"createFile","class":"Sabre\\DAV\\Server","type":"->","args":["uploads\/gerwern\/60407603\/00000004",null,null]},{"function":"httpPut","class":"Sabre\\DAV\\CorePlugin","type":"->","args":[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php","line":105,"function":"call_user_func_array","args":[[{"__class__":"Sabre\\DAV\\CorePlugin"},"httpPut"],[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","line":479,"function":"emit","class":"Sabre\\Event\\EventEmitter","type":"->","args":["method:PUT",[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"\/var\/www\/html\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php","line":254,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->","args":[{"absoluteUrl":"https:\/\/ServerName\/remote.php\/dav\/uploads\/gerwern\/60407603\/00000004","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Server.php","line":301,"function":"exec","class":"Sabre\\DAV\\Server","type":"->","args":[]},{"file":"\/var\/www\/html\/nextcloud\/apps\/dav\/appinfo\/v2\/remote.php","line":35,"function":"exec","class":"OCA\\DAV\\Server","type":"->","args":[]},{"file":"\/var\/www\/html\/nextcloud\/remote.php","line":163,"args":["\/var\/www\/html\/nextcloud\/apps\/dav\/appinfo\/v2\/remote.php"],"function":"require_once"}],"File":"\/var\/www\/html\/nextcloud\/apps\/dav\/lib\/Connector\/Sabre\/File.php","Line":200,"CustomMessage":"--"},"userAgent":"Mozilla\/5.0 (Windows) mirall\/2.6.0stable-Win64 (build 20190927) (Nextcloud)","version":"15.0.2.0"}

The output of your config.php file in /path/to/nextcloud:

<?php
$CONFIG = array (
  'instanceid' => 'XXXX',
  'passwordsalt' => 'XXXX',
  'secret' => 'XXXX',
  'trusted_domains' => 
  array (
    0 => 'xyzy.com',
  ),
  'datadirectory' => '/mnt/storage/nextcloud',
  'dbtype' => 'mysql',
  'version' => '15.0.2.0',
  'overwrite.cli.url' => 'https://xyzy.com',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nextcloud',
  'dbpassword' => 'XXXXX',
  'installed' => true,
  'twofactor_enforced' => 'false',
  'twofactor_enforced_groups' => 
  array (
  ),
  'twofactor_enforced_excluded_groups' => 
  array (
  ),
  'mail_from_address' => '',
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'mail_domain' => '',
  'mail_smtpsecure' => 'tls',
  'mail_smtpauth' => 1,
  'mail_smtphost' => 'mail.gmx.net',
  'mail_smtpport' => '587',
  'mail_smtpname' => '',
  'mail_smtppassword' => '',
  'mail_smtpauthtype' => 'LOGIN',
);

The output of your Apache log in /var/log/apache2:

[Sat Oct 12 06:25:01.705455 2019] [mpm_prefork:notice] [pid 1402] AH00163: Apache/2.4.29 (Ubuntu) Op$
[Sat Oct 12 06:25:01.705470 2019] [core:notice] [pid 1402] AH00094: Command line: '/usr/sbin/apache2'
[Sat Oct 12 06:29:26.441551 2019] [authz_core:error] [pid 9306] [client 192.168.2.1:49721] AH01630: $
[Sat Oct 12 07:48:24.936703 2019] [mpm_prefork:notice] [pid 1402] AH00169: caught SIGTERM, shutting $
[Sat Oct 12 07:49:12.433018 2019] [ssl:warn] [pid 1202] AH01909: ServerName/:port:0 server cer$
[Sat Oct 12 07:49:14.225753 2019] [ssl:warn] [pid 1600] AH01909: ServerName/:port:0 server cer$
[Sat Oct 12 07:49:14.235514 2019] [mpm_prefork:notice] [pid 1600] AH00163: Apache/2.4.29 (Ubuntu) Op$
[Sat Oct 12 07:49:14.235581 2019] [core:notice] [pid 1600] AH00094: Command line: '/usr/sbin/apache2'
[Sat Oct 12 08:09:51.511471 2019] [mpm_prefork:notice] [pid 1600] AH00169: caught SIGTERM, shutting $
[Sat Oct 12 08:11:05.140731 2019] [ssl:warn] [pid 1027] AH01909: ServerName/:port:0 server cer$
[Sat Oct 12 08:11:06.122991 2019] [ssl:warn] [pid 1522] AH01909: ServerName/:port:0 server cer$
[Sat Oct 12 08:11:06.133612 2019] [mpm_prefork:notice] [pid 1522] AH00163: Apache/2.4.29 (Ubuntu) Op$
[Sat Oct 12 08:11:06.133686 2019] [core:notice] [pid 1522] AH00094: Command line: '/usr/sbin/apache2'
[Sat Oct 12 08:27:02.324032 2019] [mpm_prefork:notice] [pid 1522] AH00169: caught SIGTERM, shutting $
[Sat Oct 12 08:27:02.437886 2019] [ssl:warn] [pid 2042] AH01909: ServerName/:port:0 server cer$
[Sat Oct 12 08:27:02.493956 2019] [ssl:warn] [pid 2051] AH01909: ServerName/:port:0 server cer$
[Sat Oct 12 08:27:02.502799 2019] [mpm_prefork:notice] [pid 2051] AH00163: Apache/2.4.29 (Ubuntu) Op$
[Sat Oct 12 08:27:02.502871 2019] [core:notice] [pid 2051] AH00094: Command line: '/usr/sbin/apache2

There is something wrong with your apache process. Did you try to restart the service?
sudo service apache2 restart
Can you show the apache configuration? Most likely there is a virtual host file in

/etc/apache2/sites-available/***.conf
That refers to your nextcloud in /var/www/html/nextcloud.

Hello,

you are probably right! I figured out, that I can acces nextcloud without trouble locally via the ip adress, after adding that to the trusted domains!

I restarted the apache2, that did not solve the problem and I did not recieve an error message.

The file from /sites-available looks like this:

<VirtualHost *:80>
ServerName NAME.hopto.org/

ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined

Redirect permanent / https://NAME.hopto.org/
</VirtualHost>

<IfModule mod_ssl.c>
SSLStaplingCache shmcb:/tmp/stapling_cache(128000)
<VirtualHost *:123>

ServerName NAME.hopto.org/

DocumentRoot /var/www/html/nextcloud

ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined

# SSL Konfiguration
SSLEngine on
SSLCertificateFile /etc/letsencrypt/live/NAME.hopto.org/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/NAME.hopto.org/privkey.pem
SSLProtocol All -SSLv2 -SSLv3 -TLSv1.1

<FilesMatch "\.(cgi|shtml|phtml|php)$">
SSLOptions +StdEnvVars
</FilesMatch>
<Directory /usr/lib/cgi-bin>
SSLOptions +StdEnvVars
</Directory>

#Nextcloud Konfiguration
<Directory /var/www/html/nextcloud/>
Options +FollowSymlinks
AllowOverride All

<IfModule mod_dav.c>
Dav off
</IfModule>

SetEnv HOME /var/www/html/nextcloud
SetEnv HTTP_HOME /var/www/html/nextcloud
</Directory>

</VirtualHost>
</IfModule>