my sql does not start any more.
Hier is the mysql.err file:

2018-03-09 18:37:46 1995689984 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2018-03-09 18:37:46 1995689984 [Note] InnoDB: The InnoDB memory heap is disabled
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-03-09 18:37:46 1995689984 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Compressed tables use zlib 1.2.8
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Using Linux native AIO
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Using generic crc32 instructions
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Initializing buffer pool, size = 80.0M
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Completed initialization of buffer pool
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Highest supported file format is Barracuda.
2018-03-09 18:37:46 1995689984 [Note] InnoDB: 128 rollback segment(s) are active.
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Waiting for purge to start
2018-03-09 18:37:46 1995689984 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.6.35-80.0 started; log sequence number 19362938
2018-03-09 18:37:46 1430254400 [Note] InnoDB: Dumping buffer pool(s) not yet started
2018-03-09 18:37:46 1995689984 [Note] Plugin 'FEEDBACK' is disabled.
2018-03-09 18:37:46 1995689984 [ERROR] Can't open and lock privilege tables: Table 'mysql.servers' doesn't exist
2018-03-09 18:37:46 1995689984 [Note] Server socket created on IP: '::'.
2018-03-09 18:37:46 1995689984 [Warning] Can't open and lock time zone table: Table 'mysql.time_zone_leap_second' doesn't exist trying to live without them
2018-03-09 18:37:46 1502742336 [Warning] Failed to load slave replication state from table mysql.gtid_slave_pos: 1146: Table 'mysql.gtid_slave_pos' doesn't exist
2018-03-09 18:37:46 1995689984 [Note] Reading of all Master_info entries succeded
2018-03-09 18:37:46 1995689984 [Note] Added new Master_info '' to hash table
2018-03-09 18:37:46 1995689984 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.1.23-MariaDB-9+deb9u1' socket: '/home/pi/.config/cqrlog/database/sock' port: 64000 Raspbian 9.0
2018-03-09 18:37:47 598d6740 InnoDB: Error: Table "mysql"."innodb_table_stats" not found.

and here comes /var/log/mysql/error.log

2018-12-23 18:59:49 1995972608 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2018-12-23 18:59:49 1995972608 [Note] InnoDB: Completed initialization of buffer pool
2018-12-23 18:59:49 1995972608 [Note] InnoDB: Highest supported file format is Barracuda.
2018-12-23 18:59:49 1995972608 [Note] InnoDB: 128 rollback segment(s) are active.
2018-12-23 18:59:49 1995972608 [Note] InnoDB: Waiting for purge to start
2018-12-23 18:59:50 1995972608 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.6.35-80.0 started; log sequence number 25888333
2018-12-23 18:59:50 1447031616 [Note] InnoDB: Dumping buffer pool(s) not yet started
2018-12-23 18:59:50 1995972608 [Note] Plugin 'FEEDBACK' is disabled.
2018-12-23 18:59:50 1995972608 [ERROR] Could not open mysql.plugin table. Some plugins may be not loaded
2018-12-23 18:59:50 1995972608 [ERROR] /usr/sbin/mysqld: unknown variable 'defaults-file=/home/pi/.config/cqrlog/database/mysql.cnf'
2018-12-23 18:59:50 1995972608 [ERROR] Aborting

2018-12-23 21:53:42 1996214272 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2018-12-23 21:53:42 1996214272 [Note] InnoDB: The InnoDB memory heap is disabled
2018-12-23 21:53:42 1996214272 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-12-23 21:53:42 1996214272 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2018-12-23 21:53:42 1996214272 [Note] InnoDB: Compressed tables use zlib 1.2.8
2018-12-23 21:53:42 1996214272 [Note] InnoDB: Using Linux native AIO
2018-12-23 21:53:42 1996214272 [Note] InnoDB: Using generic crc32 instructions
2018-12-23 21:53:42 1996214272 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2018-12-23 21:53:42 1996214272 [Note] InnoDB: Completed initialization of buffer pool
2018-12-23 21:53:43 1996214272 [Note] InnoDB: Highest supported file format is Barracuda.
2018-12-23 21:53:44 1996214272 [Note] InnoDB: 128 rollback segment(s) are active.
2018-12-23 21:53:44 1996214272 [Note] InnoDB: Waiting for purge to start
2018-12-23 21:53:44 1996214272 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.6.35-80.0 started; log sequence number 1618923
2018-12-23 21:53:44 1447031616 [Note] InnoDB: Dumping buffer pool(s) not yet started
2018-12-23 21:53:44 1996214272 [Note] Plugin 'FEEDBACK' is disabled.
2018-12-23 21:53:45 1996214272 [Note] Server socket created on IP: '127.0.0.1'.
2018-12-23 21:53:45 1996214272 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.1.23-MariaDB-9+deb9u1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 Raspbian 9.0

best regards

Frank
DB5FP