Problem converting from 2.4.8.3 to 3.1.2.1

Did you pull those SQLs from another similar post? If so, it might be helpful to everyone to consolidate similar questions, rather than asking independent questions in a single thread.

The error Call to a member function getFileId() on null in .../lib/pkp/classes/file/SubmissionFileManager.inc.php:184 is also mentioned in:

and

and

In this last thread, the user reports that this was found to be an issue with missing supplementary files on the server.