owncloud 9.0.2.2. Error

Server configuration:

Operating system: Debian Jessie 8.4
Web server: Apache/2.4.10
Database: Mysql Ver 5.5.49
PHP version: PHP 5.6.20-0+deb8u1
ownCloud version (see ownCloud admin page): 9.0.2.2


owncloud.config:
<?php
$CONFIG = array (
  'instanceid' => 'xxxxxxxxxxx',
  'passwordsalt' => 'xxxxxxxxxxx',
  'secret' => 'xxxxxxxxxxx',
  'trusted_domains' => 
  array (
    0 => 'xxx.xxx.xxx.x',
    1 => 'xxxxxxxxxxx.de',
    2 => 'owncloud.xxxxxxxxxxx.de',
  ),
  'datadirectory' => '/home/xxxxxx/owncloud_data',
  'overwrite.cli.url' => 'https://xxx.xxx.xxx.xx/owncloud',
  'dbtype' => 'mysql',
  'version' => '9.0.2.2',
  'dbname' => 'owncloud',
  'dbhost' => 'localhost',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'oc_xxxxx1',
  'dbpassword' => 'xxxxxxxxxxxxxxxxxx',
  'logtimezone' => 'UTC',
  'installed' => true,
  'mail_smtpmode' => 'smtp',
  'mail_from_address' => 'kontakt',
  'mail_domain' => 'xxxxxxxxxxxxxr.de',
  'mail_smtpsecure' => 'ssl',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtphost' => 'smtp.xxxxx.de',
  'mail_smtpauth' => 1,
  'mail_smtpport' => '465',
  'mail_smtpname' => 'xxxxxxx@xxxxxxxxxxxx.de',
  'mail_smtppassword' => '#vio2105#',
  'loglevel' => 0,
  'maintenance' => false,
  'theme' => '',
  'trashbin_retention_obligation' => 'auto',
  'updatechecker' => false,
);

.htaccess

<IfModule mod_headers.c>
  <IfModule mod_setenvif.c>
    <IfModule mod_fcgid.c>
       SetEnvIfNoCase ^Authorization$ "(.+)" XAUTHORIZATION=$1
       RequestHeader set XAuthorization %{XAUTHORIZATION}e env=XAUTHORIZATION
    </IfModule>
    <IfModule mod_proxy_fcgi.c>
       SetEnvIfNoCase Authorization "(.+)" HTTP_AUTHORIZATION=$1
    </IfModule>
  </IfModule>

  <IfModule mod_env.c>
    # Add security and privacy related headers
    Header set X-Content-Type-Options "nosniff"
    Header set X-XSS-Protection "1; mode=block"
    Header set X-Robots-Tag "none"
    Header set X-Frame-Options "SAMEORIGIN"
    Header set X-Download-Options "noopen"
    Header set X-Permitted-Cross-Domain-Policies "none"
    SetEnv modHeadersAvailable true
  </IfModule>

  # Add cache control for CSS and JS files
  <FilesMatch "\.(css|js)$">
    Header set Cache-Control "max-age=7200, public"
  </FilesMatch>
</IfModule>
<IfModule mod_php5.c>
  php_value upload_max_filesize 513M
  php_value post_max_size 513M
  php_value memory_limit 512M
  php_value mbstring.func_overload 0
  php_value always_populate_raw_post_data -1
  php_value default_charset 'UTF-8'
  php_value output_buffering 0
  <IfModule mod_env.c>
    SetEnv htaccessWorking true
  </IfModule>
</IfModule>
<IfModule mod_php7.c>
  php_value upload_max_filesize 513M
  php_value post_max_size 513M
  php_value memory_limit 512M
  php_value mbstring.func_overload 0
  php_value default_charset 'UTF-8'
  php_value output_buffering 0
  <IfModule mod_env.c>
    SetEnv htaccessWorking true
  </IfModule>
</IfModule>
<IfModule mod_rewrite.c>
  RewriteEngine on
  RewriteRule .* - [env=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
  RewriteRule ^\.well-known/host-meta /public.php?service=host-meta [QSA,L]
  RewriteRule ^\.well-known/host-meta\.json /public.php?service=host-meta-json [QSA,L]
  RewriteRule ^\.well-known/carddav /remote.php/dav/ [R=301,L]
  RewriteRule ^\.well-known/caldav /remote.php/dav/ [R=301,L]
  RewriteRule ^remote/(.*) remote.php [QSA,L]
  RewriteRule ^(build|tests|config|lib|3rdparty|templates)/.* - [R=404,L]
  RewriteCond %{REQUEST_URI} !^/.well-known/acme-challenge/.*
  RewriteRule ^(\.|autotest|occ|issue|indie|db_|console).* - [R=404,L]

  # Rewrite rules for `front_controller_active`
  Options -MultiViews
  RewriteRule ^core/js/oc.js$ index.php [PT,E=PATH_INFO:$1]
  RewriteRule ^core/preview.png$ index.php [PT,E=PATH_INFO:$1]
  RewriteCond %{REQUEST_FILENAME} !\.(css|js|svg|gif|png|html|ttf|woff|ico|jpg|jpeg)$
  RewriteCond %{REQUEST_FILENAME} !core/img/favicon.ico$
  RewriteCond %{REQUEST_FILENAME} !/remote.php
  RewriteCond %{REQUEST_FILENAME} !/public.php
  RewriteCond %{REQUEST_FILENAME} !/cron.php
  RewriteCond %{REQUEST_FILENAME} !/core/ajax/update.php
  RewriteCond %{REQUEST_FILENAME} !/status.php
  RewriteCond %{REQUEST_FILENAME} !/ocs/v1.php
  RewriteCond %{REQUEST_FILENAME} !/ocs/v2.php
  RewriteCond %{REQUEST_FILENAME} !/updater/
  RewriteCond %{REQUEST_FILENAME} !/ocs-provider/
  RewriteCond %{REQUEST_URI} !^/.well-known/acme-challenge/.*
</IfModule>
<IfModule mod_mime.c>
  AddType image/svg+xml svg svgz
  AddEncoding gzip svgz
</IfModule>
<IfModule mod_dir.c>
  DirectoryIndex index.php index.html
</IfModule>
AddDefaultCharset utf-8
Options -Indexes
<IfModule pagespeed_module>
  ModPagespeed Off
</IfModule>
#### DO NOT CHANGE ANYTHING ABOVE THIS LINE ####

ErrorDocument 403 /owncloud/core/templates/403.php
ErrorDocument 404 /owncloud/core/templates/404.php
<IfModule mod_rewrite.c>
  RewriteRule . index.php [PT,E=PATH_INFO:$1]
  RewriteBase /owncloud
  <IfModule mod_env.c>
    SetEnv front_controller_active true
    <IfModule mod_dir.c>
      DirectorySlash off
    </IfModule>
  </IfModule>
</IfModule>

apache config:
/etc/apache2/sites-enabled/owncloud.conf

<VirtualHost *:80>
   ServerName MyDomain.de
   Redirect permanent / https://MyDomain.de/
</VirtualHost>

/etc/apache2/sites-enabled/ssl.conf
    NameVirtualHost *:443
    SSLCertificateFile /etc/ssl/certs/apache.crt
    SSLCertificateKeyFile /etc/ssl/private/apache.key



<VirtualHost *:443>
    SSLEngine on

    ServerName MyDomain.de
    DocumentRoot /var/www/owncloud/
   Header always add Strict-Transport-Security "max-age=15768000; includeSubDomains; preload"
</VirtualHost>

/etc/apache2/sites-enabled/000-default.conf:

<VirtualHost *:80>
ServerAdmin webmaster@localhost

    DocumentRoot /var/www/webdesign/
    <Directory />
            Options FollowSymLinks
            AllowOverride All
    </Directory>
    <Directory /var/www/webdesign/>
            Options FollowSymLinks
            AllowOverride All
            Order allow,deny
            allow from all
    </Directory>

    ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
    <Directory "/usr/lib/cgi-bin">
            AllowOverride None
            Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
            Order allow,deny
            Allow from all
    </Directory>

    ErrorLog ${APACHE_LOG_DIR}/error.log

    # Possible values include: debug, info, notice, warn, error, crit,
    # alert, emerg.
    LogLevel warn

    CustomLog ${APACHE_LOG_DIR}/access.log combined