UPDATE command denied to user "ispcp"@"localhost" for table "mail_users"
User did have read access (I test only if I can login to database, not all rights - I`ll improve this later). Thats why it was not reported that he can not connect, and only failed at later step (first DELETE operation). Also script reuse database and user for database from ispcp if old name was ispcp, database is keep and updated to news structure. Restricting database user is not an option since on migration / setup some checks are done to `information_schema` too, and backup process also need access to all users databases.