Recently I had an error message while migrating and old Joomla! 1.5 site to the new Joomla! 2.5, jupgrade failed with “Migrating undefined” error.
After digging in the code I found a solution:
You have to edit two files:
and insert the following line near the top of the script:
When done (after the failed upgrade), you can retry the migration checking the following options in Jupgrade configuration: