Cannot Access Database after Upgrade to 9.1.4

Hey,

today I was synchronizing some files, and at the same time thought "hey, it would be a nice idea to update my owncloud". So i ran "apt upgrade".
about 54% in, the sync process froze, with the error message "server-replied: Internal Server Error".

the output for the "apt upgrade" contained this error message:

Unpacking owncloud-files (9.1.4-1.1) over (9.1.3-1.1) ...
Preparing to unpack .../owncloud-deps-php5_9.1.4-1.1_all.deb ...
owncloud-deps-php5: occ maintenance:mode --on
An unhandled exception has been thrown:
exception 'Doctrine\DBAL\DBALException' with message 'Failed to connect to the database: An exception occured in driver: SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' in /var/www/owncloud/lib/private/DB/Connection.php:58
Stack trace:
0 /var/www/owncloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(429): OC\DB\Connection->connect()
1 /var/www/owncloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(389): Doctrine\DBAL\Connection->getDatabasePlatformVersion()
2 /var/www/owncloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(328): Doctrine\DBAL\Connection->detectDatabasePlatform()
3 /var/www/owncloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(621): Doctrine\DBAL\Connection->getDatabasePlatform()
4 /var/www/owncloud/lib/private/DB/Connection.php(141): Doctrine\DBAL\Connection->setTransactionIsolation(2)
5 /var/www/owncloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/DriverManager.php(172): OC\DB\Connection->__construct(Array, Object(Doctrine\DBAL\Driver\PDOMySql\Driver), Object(Doctrine\DBAL\Configuration), Object(Doctrine\Common\EventManager))
6 /var/www/owncloud/lib/private/DB/ConnectionFactory.php(122): Doctrine\DBAL\DriverManager::getConnection(Array, Object(Doctrine\DBAL\Configuration), Object(Doctrine\Common\EventManager))
7 /var/www/owncloud/lib/private/Server.php(414): OC\DB\ConnectionFactory->getConnection('mysql', Array)
8 /var/www/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
9 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(102): Pimple\Container->offsetGet('DatabaseConnect...')
10 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('DatabaseConnect...')
11 /var/www/owncloud/lib/private/Server.php(973): OC\ServerContainer->query('DatabaseConnect...')
12 /var/www/owncloud/lib/private/Server.php(219): OC\Server->getDatabaseConnection()
13 /var/www/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
14 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(102): Pimple\Container->offsetGet('OC\Authenticati...')
15 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('OC\Authenticati...')
16 /var/www/owncloud/lib/private/Server.php(223): OC\ServerContainer->query('OC\Authenticati...')
17 /var/www/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
18 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(102): Pimple\Container->offsetGet('OC\Authenticati...')
19 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('OC\Authenticati...')
20 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(150): OC\ServerContainer->query('OC\Authenticati...')
21 /var/www/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(109): OC\AppFramework\Utility\SimpleContainer->OC\AppFramework\Utility{closure}(Object(OC\Server))
22 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(102): Pimple\Container->offsetGet('OC\Authenticati...')
23 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('OC\Authenticati...')
24 /var/www/owncloud/lib/private/Server.php(238): OC\ServerContainer->query('OC\Authenticati...')
25 /var/www/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
26 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(102): Pimple\Container->offsetGet('UserSession')
27 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('UserSession')
28 /var/www/owncloud/lib/private/Server.php(850): OC\ServerContainer->query('UserSession')
29 /var/www/owncloud/lib/private/Server.php(458): OC\Server->getUserSession()
30 /var/www/owncloud/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
31 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(102): Pimple\Container->offsetGet('AppManager')
32 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('AppManager')
33 /var/www/owncloud/lib/private/Server.php(1150): OC\ServerContainer->query('AppManager')
34 /var/www/owncloud/lib/private/legacy/app.php(285): OC\Server->getAppManager()
35 /var/www/owncloud/lib/private/legacy/app.php(106): OC_App::getEnabledApps()
36 /var/www/owncloud/lib/base.php(573): OC_App::loadApps(Array)
37 /var/www/owncloud/lib/base.php(973): OC::init()
38 /var/www/owncloud/console.php(58): require_once('/var/www/ownclo...')
39 /var/www/owncloud/occ(11): require_once('/var/www/ownclo...')
40 {main}Unpacking owncloud-deps-php5 (9.1.4-1.1) over (9.1.3-1.1) ...
Conf owncloud disabled.
To activate the new configuration, you need to run:
service apache2 reload

and then continued to install.
/var/log/owncloud.log, /var/log/mysql.log and /var/log/mysql.err were empty, only in /var/log/error.log there was something:

170208 16:38:38 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 16:38:38 [Note] InnoDB: The InnoDB memory heap is disabled
170208 16:38:38 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 16:38:38 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 16:38:38 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 16:38:38 [Note] InnoDB: Using Linux native AIO
170208 16:38:38 [Note] InnoDB: Using CPU crc32 instructions
170208 16:38:38 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 16:38:38 [Note] InnoDB: Completed initialization of buffer pool
170208 16:38:38 [Note] InnoDB: Highest supported file format is Barracuda.
170208 16:38:38 [Note] InnoDB: 128 rollback segment(s) are active.
170208 16:38:38 [Note] InnoDB: Waiting for purge to start
170208 16:38:38 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848738
170208 16:38:40 [Note] InnoDB: FTS optimize thread exiting.
170208 16:38:40 [Note] InnoDB: Starting shutdown...
170208 16:38:40 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 16:38:42 [Note] InnoDB: Shutdown completed; log sequence number 14848748
170208 16:38:42 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 16:38:42 [Note] InnoDB: The InnoDB memory heap is disabled
170208 16:38:42 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 16:38:42 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 16:38:42 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 16:38:42 [Note] InnoDB: Using Linux native AIO
170208 16:38:42 [Note] InnoDB: Using CPU crc32 instructions
170208 16:38:42 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 16:38:42 [Note] InnoDB: Completed initialization of buffer pool
170208 16:38:42 [Note] InnoDB: Highest supported file format is Barracuda.
170208 16:38:42 [Note] InnoDB: 128 rollback segment(s) are active.
170208 16:38:42 [Note] InnoDB: Waiting for purge to start
170208 16:38:42 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848748
170208 16:38:42 [Note] InnoDB: FTS optimize thread exiting.
170208 16:38:42 [Note] InnoDB: Starting shutdown...
170208 16:38:43 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 16:38:45 [Note] InnoDB: Shutdown completed; log sequence number 14848758
170208 16:38:45 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 16:38:45 [Note] InnoDB: The InnoDB memory heap is disabled
170208 16:38:45 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 16:38:45 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 16:38:45 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 16:38:45 [Note] InnoDB: Using Linux native AIO
170208 16:38:45 [Note] InnoDB: Using CPU crc32 instructions
170208 16:38:45 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 16:38:45 [Note] InnoDB: Completed initialization of buffer pool
170208 16:38:45 [Note] InnoDB: Highest supported file format is Barracuda.
170208 16:38:45 [Note] InnoDB: 128 rollback segment(s) are active.
170208 16:38:45 [Note] InnoDB: Waiting for purge to start
170208 16:38:45 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848758
170208 16:38:45 [Note] Plugin 'FEEDBACK' is disabled.
170208 16:38:45 [Note] InnoDB: FTS optimize thread exiting.
170208 16:38:45 [Note] InnoDB: Starting shutdown...
170208 16:38:46 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 16:38:48 [Note] InnoDB: Shutdown completed; log sequence number 14848768
170208 16:38:48 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 16:38:48 [Note] InnoDB: The InnoDB memory heap is disabled
170208 16:38:48 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 16:38:48 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 16:38:48 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 16:38:48 [Note] InnoDB: Using Linux native AIO
170208 16:38:48 [Note] InnoDB: Using CPU crc32 instructions
170208 16:38:48 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 16:38:48 [Note] InnoDB: Completed initialization of buffer pool
170208 16:38:48 [Note] InnoDB: Highest supported file format is Barracuda.
170208 16:38:48 [Note] InnoDB: 128 rollback segment(s) are active.
170208 16:38:48 [Note] InnoDB: Waiting for purge to start
170208 16:38:48 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848768
170208 16:38:48 [Note] Plugin 'FEEDBACK' is disabled.
170208 16:38:48 [Note] InnoDB: FTS optimize thread exiting.
170208 16:38:48 [Note] InnoDB: Starting shutdown...
170208 16:38:49 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 16:38:51 [Note] InnoDB: Shutdown completed; log sequence number 14848778
170208 16:38:51 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 16:38:51 [Note] InnoDB: The InnoDB memory heap is disabled
170208 16:38:51 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 16:38:51 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 16:38:51 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 16:38:51 [Note] InnoDB: Using Linux native AIO
170208 16:38:51 [Note] InnoDB: Using CPU crc32 instructions
170208 16:38:51 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 16:38:51 [Note] InnoDB: Completed initialization of buffer pool
170208 16:38:51 [Note] InnoDB: Highest supported file format is Barracuda.
170208 16:38:51 [Note] InnoDB: 128 rollback segment(s) are active.
170208 16:38:51 [Note] InnoDB: Waiting for purge to start
170208 16:38:51 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848778
170208 16:38:51 [Note] Plugin 'FEEDBACK' is disabled.
170208 16:38:51 [Note] InnoDB: FTS optimize thread exiting.
170208 16:38:51 [Note] InnoDB: Starting shutdown...
170208 16:38:52 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 16:38:54 [Note] InnoDB: Shutdown completed; log sequence number 14848788
170208 17:03:33 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:03:33 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:03:33 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:03:33 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:03:33 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:03:33 [Note] InnoDB: Using Linux native AIO
170208 17:03:33 [Note] InnoDB: Using CPU crc32 instructions
170208 17:03:33 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:03:33 [Note] InnoDB: Completed initialization of buffer pool
170208 17:03:33 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:03:33 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:03:33 [Note] InnoDB: Waiting for purge to start
170208 17:03:33 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848808
170208 17:03:35 [Note] InnoDB: FTS optimize thread exiting.
170208 17:03:35 [Note] InnoDB: Starting shutdown...
170208 17:03:36 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:03:38 [Note] InnoDB: Shutdown completed; log sequence number 14848818
170208 17:03:38 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:03:38 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:03:38 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:03:38 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:03:38 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:03:38 [Note] InnoDB: Using Linux native AIO
170208 17:03:38 [Note] InnoDB: Using CPU crc32 instructions
170208 17:03:38 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:03:38 [Note] InnoDB: Completed initialization of buffer pool
170208 17:03:38 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:03:39 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:03:39 [Note] InnoDB: Waiting for purge to start
170208 17:03:39 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848818
170208 17:03:39 [Note] InnoDB: FTS optimize thread exiting.
170208 17:03:39 [Note] InnoDB: Starting shutdown...
170208 17:03:40 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:03:41 [Note] InnoDB: Shutdown completed; log sequence number 14848828
170208 17:03:42 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:03:42 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:03:42 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:03:42 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:03:42 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:03:42 [Note] InnoDB: Using Linux native AIO
170208 17:03:42 [Note] InnoDB: Using CPU crc32 instructions
170208 17:03:42 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:03:42 [Note] InnoDB: Completed initialization of buffer pool
170208 17:03:42 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:03:42 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:03:42 [Note] InnoDB: Waiting for purge to start
170208 17:03:42 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848828
170208 17:03:42 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:03:42 [Note] InnoDB: FTS optimize thread exiting.
170208 17:03:42 [Note] InnoDB: Starting shutdown...
170208 17:03:43 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:03:45 [Note] InnoDB: Shutdown completed; log sequence number 14848838
170208 17:03:45 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:03:45 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:03:45 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:03:45 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:03:45 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:03:45 [Note] InnoDB: Using Linux native AIO
170208 17:03:45 [Note] InnoDB: Using CPU crc32 instructions
170208 17:03:45 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:03:45 [Note] InnoDB: Completed initialization of buffer pool
170208 17:03:45 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:03:46 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:03:46 [Note] InnoDB: Waiting for purge to start
170208 17:03:46 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848838
170208 17:03:46 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:03:46 [Note] InnoDB: FTS optimize thread exiting.
170208 17:03:46 [Note] InnoDB: Starting shutdown...
170208 17:03:47 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:03:48 [Note] InnoDB: Shutdown completed; log sequence number 14848848
170208 17:03:49 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:03:49 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:03:49 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:03:49 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:03:49 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:03:49 [Note] InnoDB: Using Linux native AIO
170208 17:03:49 [Note] InnoDB: Using CPU crc32 instructions
170208 17:03:49 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:03:49 [Note] InnoDB: Completed initialization of buffer pool
170208 17:03:49 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:03:49 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:03:49 [Note] InnoDB: Waiting for purge to start
170208 17:03:49 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848848
170208 17:03:49 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:03:49 [Note] InnoDB: FTS optimize thread exiting.
170208 17:03:49 [Note] InnoDB: Starting shutdown...
170208 17:03:50 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:03:52 [Note] InnoDB: Shutdown completed; log sequence number 14848858
170208 17:03:52 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:03:52 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:03:52 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:03:52 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:03:52 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:03:52 [Note] InnoDB: Using Linux native AIO
170208 17:03:52 [Note] InnoDB: Using CPU crc32 instructions
170208 17:03:52 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:03:52 [Note] InnoDB: Completed initialization of buffer pool
170208 17:03:52 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:03:52 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:03:52 [Note] InnoDB: Waiting for purge to start
170208 17:03:52 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848858
170208 17:03:52 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:03:52 [Note] InnoDB: FTS optimize thread exiting.
170208 17:03:52 [Note] InnoDB: Starting shutdown...
170208 17:03:53 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:03:55 [Note] InnoDB: Shutdown completed; log sequence number 14848868
170208 17:15:17 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:15:17 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:15:17 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:15:17 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:15:17 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:15:17 [Note] InnoDB: Using Linux native AIO
170208 17:15:17 [Note] InnoDB: Using CPU crc32 instructions
170208 17:15:17 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:15:17 [Note] InnoDB: Completed initialization of buffer pool
170208 17:15:17 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:15:17 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:15:17 [Note] InnoDB: Waiting for purge to start
170208 17:15:17 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848878
170208 17:15:19 [Note] InnoDB: FTS optimize thread exiting.
170208 17:15:19 [Note] InnoDB: Starting shutdown...
170208 17:15:19 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:15:21 [Note] InnoDB: Shutdown completed; log sequence number 14848888
170208 17:15:21 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:15:21 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:15:21 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:15:21 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:15:21 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:15:21 [Note] InnoDB: Using Linux native AIO
170208 17:15:21 [Note] InnoDB: Using CPU crc32 instructions
170208 17:15:21 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:15:21 [Note] InnoDB: Completed initialization of buffer pool
170208 17:15:21 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:15:22 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:15:22 [Note] InnoDB: Waiting for purge to start
170208 17:15:22 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848888
170208 17:15:22 [Note] InnoDB: FTS optimize thread exiting.
170208 17:15:22 [Note] InnoDB: Starting shutdown...
170208 17:15:23 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:15:24 [Note] InnoDB: Shutdown completed; log sequence number 14848898
170208 17:15:25 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:15:25 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:15:25 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:15:25 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:15:25 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:15:25 [Note] InnoDB: Using Linux native AIO
170208 17:15:25 [Note] InnoDB: Using CPU crc32 instructions
170208 17:15:25 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:15:25 [Note] InnoDB: Completed initialization of buffer pool
170208 17:15:25 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:15:25 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:15:25 [Note] InnoDB: Waiting for purge to start
170208 17:15:25 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848898
170208 17:15:25 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:15:25 [Note] InnoDB: FTS optimize thread exiting.
170208 17:15:25 [Note] InnoDB: Starting shutdown...
170208 17:15:26 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:15:28 [Note] InnoDB: Shutdown completed; log sequence number 14848908
170208 17:15:28 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:15:28 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:15:28 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:15:28 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:15:28 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:15:28 [Note] InnoDB: Using Linux native AIO
170208 17:15:28 [Note] InnoDB: Using CPU crc32 instructions
170208 17:15:28 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:15:28 [Note] InnoDB: Completed initialization of buffer pool
170208 17:15:28 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:15:28 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:15:28 [Note] InnoDB: Waiting for purge to start
170208 17:15:28 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848908
170208 17:15:28 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:15:28 [Note] InnoDB: FTS optimize thread exiting.
170208 17:15:28 [Note] InnoDB: Starting shutdown...
170208 17:15:29 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:15:31 [Note] InnoDB: Shutdown completed; log sequence number 14848918
170208 17:15:31 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:15:31 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:15:31 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:15:31 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:15:31 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:15:31 [Note] InnoDB: Using Linux native AIO
170208 17:15:31 [Note] InnoDB: Using CPU crc32 instructions
170208 17:15:31 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:15:31 [Note] InnoDB: Completed initialization of buffer pool
170208 17:15:31 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:15:31 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:15:31 [Note] InnoDB: Waiting for purge to start
170208 17:15:31 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848918
170208 17:15:31 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:15:31 [Note] InnoDB: FTS optimize thread exiting.
170208 17:15:31 [Note] InnoDB: Starting shutdown...
170208 17:15:32 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:15:34 [Note] InnoDB: Shutdown completed; log sequence number 14848928
170208 17:15:35 [Note] InnoDB: Using mutexes to ref count buffer pool pages
170208 17:15:35 [Note] InnoDB: The InnoDB memory heap is disabled
170208 17:15:35 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
170208 17:15:35 [Note] InnoDB: GCC builtin _atomicthread_fence() is used for memory barrier
170208 17:15:35 [Note] InnoDB: Compressed tables use zlib 1.2.8
170208 17:15:35 [Note] InnoDB: Using Linux native AIO
170208 17:15:35 [Note] InnoDB: Using CPU crc32 instructions
170208 17:15:35 [Note] InnoDB: Initializing buffer pool, size = 128.0M
170208 17:15:35 [Note] InnoDB: Completed initialization of buffer pool
170208 17:15:35 [Note] InnoDB: Highest supported file format is Barracuda.
170208 17:15:35 [Note] InnoDB: 128 rollback segment(s) are active.
170208 17:15:35 [Note] InnoDB: Waiting for purge to start
170208 17:15:35 [Note] InnoDB: Percona XtraDB 5.6.34-79.1 started; log sequence number 14848928
170208 17:15:35 [Note] Plugin 'FEEDBACK' is disabled.
170208 17:15:35 [Note] InnoDB: FTS optimize thread exiting.
170208 17:15:35 [Note] InnoDB: Starting shutdown...
170208 17:15:36 [Note] InnoDB: Waiting for page_cleaner to finish flushing of buffer pool
170208 17:15:37 [Note] InnoDB: Shutdown completed; log sequence number 14848938

I then tried this solution: https://central.owncloud.org/t/failed-to-connect-to-the-database-access-denied-for-user-root-localhost-in-var-www-owncloud-lib-private-db-connection-php/2321/3
(except that I "reinstalled owncloud" with a simple apt-get, not with a full repetition of the manual installation guide, but that shouldnt make a difference.)

but even after that it doesnt work, the web interface still displays the maintenance message.

what can I do to fix this?

If your database is down / not running then ownCloud won't be able to do the upgrade. You might be able to get your instance up and running again by doing the following steps:

  1. cd /var/www/owncloud
  2. ./occ maintenance:mode --off
  3. ./occ upgrade
1 Like

yes, that worked :slight_smile: thank you :slight_smile: