I recently encountered this error on Disposeamail – a free disposable email site of mine that uses MySQL heavily for storing all incoming mail through an email pipe script.

I did a lot of researching, and basically, there are a few primary culprits I was able to identify that will hopefully save you some time.

Check your /tmp directory

MySQL will produce this error sometimes when the temp directory is not writeable.

1. Ensure that /tmp (and/or /var/tmp) has the correct permissions (777)
2. Check the my.cnf file and search for a  tmpdir =/tmp flag. Ensure the value is pointing to the correct temp directory.
3. Ensure your /tmp directory is not full

Check your my.cnf

1. If you made changes recently, revert them and restart MySQL (especially InnoDB Buffer Pool settings)
2. Restore my.cnf.back is there is one
3. If you are using InnoDB tables , ensure the  skip-innodb line in my.cnf is commented out or removed.

Clear InnoDB Log Files

This step ONLY APPLIES IF THE ABOVE STEPS DID NOT WORK.

Read the  MySQL Manual page on removing InnoDB log files for a safer backup and restoration procedures. Basically, the steps are:

1. Shut down MySQL
2. Remove ib_logfile* files from the MySQL data directory (move them or rename them if you want to be safe)
3. Re-start MySQL

My specific problem was that somehow the “skip-innodb” line got added back into my “my.cnf” file, so MySQL was expecting a different table format when loading data. I suspect this had something to do with my cPanel/WHM setup overwriting the file, but I’ll never know for sure.

Good Luck!