MySQL 5.6 service cannot be started. Different errors can be found in Event Viewer. The following error can be found in
InnoDB: No valid checkpoint found.
InnoDB: If you are attempting downgrade from MySQL 5.7.9 or later,
InnoDB: please refer to http://dev.mysql.com/doc/refman/5.6/en/upgrading-downgrading.html
InnoDB: If this error appears when you are creating an InnoDB database,
InnoDB: the problem may be that during an earlier attempt you managed
InnoDB: to create the InnoDB data files, but log file creation failed.
InnoDB: If that is the case, please refer to
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/error-creating-innodb.html 2017-01-31 17:34:23 4476
[ERROR] Plugin 'InnoDB' init function returned error. 2017-01-31 17:34:23 4476
[ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 2017-01-31 17:34:23 4476
[ERROR] Unknown/unsupported storage engine: INNODB
MySQL 5.7 was never installed.
Rename the following files and tr to start the service.