I had a look into the syslog file of my debian server and found out that there are innodb errors spamming the logfile.
It seems that it has to do something with the summer and wintertime.
mysqld: 2018-11-10 14:06:49 7fe0b5287b00 InnoDB: Error: Column last_update in table "mysql"."innodb_table_stats" is INT UNSIGNED NOT NULL but should be BINARY(4) NOT NULL (type mismatch). mysqld: 2018-11-10 14:06:49 7fe0b5287b00 InnoDB: Error: Fetch of persistent statistics requested for table "mysql"."gtid_slave_pos" but the required system tables mysql.innodb_table_stats and mysql.innodb_index_stats are not present or have unexpected structure. Using transient stats instead.
mattionline:~# mysqldump -p --events --quick --single-transaction mysql > mysql-dump.sql Enter password: mattionline:~# mysql mysql < mysql-dump.sql ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) mattionline:~# mysql -p mysql < mysql-dump.sql Enter password: mattionline:~# systemctl restart mysql
Export the database to a sql file and directly import it again (mysql server don’t need to be stopped).
After the restart of the mysql server the innodb errors disappeared.