Is possible to mysql change some engine tables automatically? I have 3 WordPress blog hosted on cPanel using MySQL. All 3 of them were working fine until yesterday. Now, the support says that &ldquo;some tables changed from 'MyISAM' to InnoDB&rdquo;.

In the logs I get:

[mydb.wp_usermeta] Error: Unknown storage engine 'InnoDB'
[mydb.wp_usermeta] error: Corrupt


And the same for other tables.

I don't know why those tables changed the engine. Is it possible for MySQL to have changed it automatically for some reason?
SHOW VARIABLES LIKE `%engine%`;


Of interest are default_storage_engine, which was MyISAM in older versions, but is now InnoDB.  This comes into play when you do CREATE TABLE without including ENGINE=....

Also of interest is enforce_storage_engine.  This strengthens the previous setting by not letting you create a table of Engine other than the default.

When changing (ALTER TABLE .. ENGINE=..) a table from one engine to another, there are some number of potential pitfalls.  I cover MyISAM --> InnoDB in here.

Did you recently upgrade MySQL?  If so, any number of problems can occur if the upgrade failed to run mysql_upgrade.

What version of MySQL are you running?

Please provide the recent contents of mysqld.err.

Please provide ls -ld /tmp

Are you using RoundCube?  The bug seems to be related to their installation.