Nextcloud version (eg, 10.0.2): 11.0.3
Operating system and version (eg, Ubuntu 16.04): mutualised ovh site
Apache or nginx version (eg, Apache 2.4.25):
PHP version (eg, 5.6): 5.6.3
Database mysql 5.5.55
Is this the first time you’ve seen this error?: yes
The issue you are facing:
Since a crash due to users. I rebuild from a backup my nextcloud ( clean the server and mysql database.Upload my backup and corespondind database) and since my clients are synchronizing well but the webinterface doesn show new files and no activity even if i upload file directly on the web interface. In view of i can’t access to ./occ files:scan because i’m on a mutualised server , do you have any workarround to make my server up and running again?
The output of your Nextcloud log in Admin > Logging:
Fatal remote An exception occurred while executing ‘SELECT uid, displayname FROM oc_users WHERE LOWER(uid) = LOWER(?)’ with params [“XXXXX”]: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away 2017-07-24T08:18:06+0200
Error PHP Doctrine\DBAL\Exception\DriverException: An exception occurred while executing ‘SELECT uid, displayname FROM oc_users WHERE LOWER(uid) = LOWER(?)’ with params [“XXXXXl”]: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away at /home/fablaborkr/www/cloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php#116
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
‘instanceid’ => ‘XXXXXX’,
‘passwordsalt’ => ‘XXXXXX’,
‘secret’ => ‘XXXXXXX’,
‘trusted_domains’ =>
array (
0 => ‘XXXXXXX’,
),
‘datadirectory’ => XXXXX’,
‘overwrite.cli.url’ => ‘XXXXX’,
‘dbtype’ => ‘mysql’,
‘version’ => ‘11.0.3.2’,
‘dbname’ => ‘XXXXXXX’,
‘dbhost’ => ‘XXXXXXXX’,
‘dbtableprefix’ => ‘oc_’,
‘dbuser’ => ‘XXXXXXXXX’,
‘dbpassword’ => ‘XXXXXXX’,
‘dbdriveroptions’ =>
array (
1002 => ‘SET wait_timeout = 28800’,
),
‘installed’ => true,
‘default_language’ => ‘fr’,
‘knowledgebaseenabled’ => true,
‘enable_avatars’ => true,
‘allow_user_to_change_display_name’ => true,
‘remember_login_cookie_lifetime’ => 2592000,
‘session_lifetime’ => 345600,
‘session_keepalive’ => true,
‘mail_domain’ => ‘XXXXXX’,
‘mail_from_address’ => ‘XXXXXXX’,
‘mail_smtpdebug’ => false,
‘mail_smtpmode’ => ‘php’,
‘appcodechecker’ => true,
‘updatechecker’ => true,
‘has_internet_connection’ => true,
‘check_for_working_htaccess’ => true,
‘config_is_read_only’ => false,
‘filesystem_check_changes’ => 1,
‘versions_retention_obligation’ => ‘8,30’,
‘trashbin_retention_obligation’ => ‘auto’,
‘activity_expire_days’ => 60,
‘log_type’ => ‘owncloud’,
‘logfile’ => ‘/var/log/nextcloud.log’,
‘loglevel’ => 1,
‘syslog_tag’ => ‘NextCloud’,
‘logtimezone’ => ‘UTC’,
‘memcache.local’ => ‘\OC\Memcache\ArrayCache’,
‘forcessl’ => true,
‘theme’ => ‘’,
‘maintenance’ => false,
‘htaccess.RewriteBase’ => ‘/’,
);
The output of your Apache/nginx/system log in /var/log/____:
can’t access to it
Remember, this information may be requested if it isn’t supplied; for fastest response please provide as much as you can 
Feel free to use a pastebin service, otherwise log files can be indented with 4 spaces on each line to present them in a friendlier way on the forum.