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In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 20.0.5): 26.0.11
Operating system and version (eg, Ubuntu 20.04): shard hosting (do not know)
Apache or nginx version (eg, Apache 2.4.25): shared hosting (do not know)
PHP version (eg, 7.4): 8.0.22
The issue you are facing:
Performed an update with the updater. When the page reloaded I got a blank white page.
Is this the first time you’ve seen this error? (Y/N): yes
Steps to replicate it:
- Use Updated from 25.0.5
The output of your Nextcloud log in Admin > Logging:
{"reqId":"ZD00xQtrR7dMmrsQhK1icwAAAB0","level":3,"time":"2023-04-17T12:00:05+00:00","remoteAddr":"8xxxx9","user":"--","app":"PHP","method":"PROPFIND","url":"/remote.php/dav/files/user/","message":"include(): Failed opening '/var/www/vhosts/host/httpdocs/nextcloud/apps/support/lib//AppInfo/Application.php' for inclusion (include_path='/var/www/vhosts/url/nextcloud/3rdparty/pear/archive_tar:/var/www/vhosts/URL/nextcloud/3rdparty/pear/console_getopt:/var/www/vhosts/URL/nextcloud/3rdparty/pear/pear-core-minimal/src:/var/www/vhosts/innobiz.de/nextcloud/3rdparty/pear/pear_exception:/var/www/vhosts/URL/nextcloud/apps') at /var/www/vhosts/URL/nextcloud/lib/composer/composer/ClassLoader.php#578","userAgent":"Mozilla/5.0 (Windows) mirall/3.0.3stable-Win64 (build 20201029) (Nextcloud)","version":"25.0.5.1","data":{"app":"PHP"}}
{"reqId":"ZD004AtrR7dMmrsQhK1ipwAAAAM","level":3,"time":"2023-04-17T12:00:32+00:00","remoteAddr":"82.135.83.89","user":"--","app":"PHP","method":"GET","url":"/ocs/v2.php/apps/notifications/api/v2/notifications?format=json","message":"include(/var/www/vhosts/host/httpdocs/nextcloud/apps/activity/lib//AppInfo/Application.php): Failed to open stream: No such file or directory at /var/www/vhosts/URL/nextcloud/lib/composer/composer/ClassLoader.php#578","userAgent":"Mozilla/5.0 (Windows) mirall/3.0.3stable-Win64 (build 20201029) (Nextcloud)","version":"25.0.5.1","data":{"app":"PHP"}}
Before the update the log is cluttered (26 MB) with these lines. They are there after the update plus messages that other users cannot connect.
"message":"include(/var/www/vhosts/host/httpdocs/nextcloud/apps/nextcloud_announcements/lib//AppInfo/Application.php): Failed to open stream: No such file or directory at /var/www/vhosts/URL/nextcloud/lib/composer/composer/ClassLoader.php#578","userAgent":"iOS/16.1.1 (20B101) dataaccessd/1.0","version":"25.0.5.1","data":{"app":"PHP"
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
'dbtype' => 'mysql',
'version' => '25.0.5.1',
'dbname' => 'OC_nc',
'dbhost' => '127.0.0.1:xxxx',
'dbtableprefix' => 'oc_',
'dbuser' => 'user',
'dbpassword' => 'password!',
'default_phone_region' => 'DE',
'installed' => true,
'forceSSLforSubdomains' => true,
'theme' => '',
'maintenance' => false,
'loglevel' => 2,
'trashbin_retention_obligation' => 30,
'trashbin_auto_expire' => true,
'appstoreenabled' => true,
'logtimezone' => 'UTC',
'mail_from_address' => 'owncloud',
'mail_smtpmode' => 'smtp',
'mail_domain' => 'domain.de',
'mail_smtpsecure' => 'ssl',
'mail_sendmailmode' => 'smtp',
'mail_smtpauthtype' => 'LOGIN',
'mail_smtpauth' => 1,
'mail_smtphost' => 'host',
'mail_smtpport' => '465',
'app_install_overwrite' =>
array (
0 => 'occweb',
),
'mysql.utf8mb4' => true,
'updater.secret' => 'adsfasdf',
);
The output of your Apache/nginx/system log in /var/log/____:
empty
PASTE HERE
not sure where to find additional information
Can I undo this update? A backup was created but know I read that I also had to do database backup. Was not aware that I need to do this manually.