Access denied
MySQL server has gone away
Can't connect to [local] MySQL server
Host '...' is blocked
Too many connections
Some non-transactional changed tables couldn't be rolled back
Out of memory
Packet too large
The table is full
Can't create/write to file
Commands out of sync
Ignoring user
Table 'xxx' doesn't exist
Can't initialize character set xxx
File not found
Обращайтесь к разделу section 4.2.6 Как работает система привилегий. Особо следует изучить раздел section 4.2.11 Причины появления ошибок Access denied ("в доступе отказано").