After upgrading from version 2.1 to 3.1 following the upgrade path 2.1 > 2.2 > 2.7 > 3.1 there is now an issue when trying to view the 'List assignments that have not been upgraded'.

With debugging off I get a http 500 error, after turning debugging on I got this error message.

Fatal error: Cannot use object of type stdClass as array in /lib/tablelib.php on line 487

I first thought this may have been an issue with just this upgrade, however I replicated the issue by upgrading a clean 2.1 site following the same upgrade path.