This page lists common migrator errors and their solutions
This is usually caused by having a third party extension installed on your Joomla! 1.0 site that has hacked the core Joomla! tables and added new fields. If the extension in question has been properly written, uninstalling it should resolve the problem. If it doesn't, identifying the table that has the extra field in it and removing this field will resolve this issue.
Examples of extensions that are known to do this (incomplete):
This occurs when you have incorrectly specified a prefix or you previous entered the incorrect prefix and haven't replaced your SQL file. The prefix for all migrations is "jos_" which is replaced when the SQL file is created. Keep in mind that you need to replace the migrate.sql file before each migration with a clean file as the migrate.sql file is changed in the process.
This usually occurs with a message about either the menu or modules table. This is caused by one of two things: the wrong prefix is entered or the files are unwriteable. If you put in the wrong prefix, replace the migrate.sql file with a new copy and enter the prefix "jos_". If the files are unwriteable, ensure that the installer can write to the following locations: