Re: Restore backup leaves one database with no access

[Rick James]

The `mysql` database contains GRANT information for users, plus related stuff. The format usually changes between major versions (5.0 to 5.1, in your case). After reloading 5.0 data into a 5.1 server, you need to run mysql_upgrade. The following message is one clue that you loaded `mysql` without upgrading it:
"Unkown column ‘Event_priv’ in ‘field list’"

Alternatively, you could avoid dumping and/or reloading `mysql`. (In later versions, one needs to avoid `information_schema` and `performance_schema` for other reasons.)

> I am told mysql is already upgraded are you sure you want to run it again.

Probably the memory of having run mysql_upgrade is sitting in some place that you are not overwriting each time you reload.

mysqldump can take a list of databases; specify just your application databases instead of dumping all the databases.