Hi @Carlo_Manuali,
The error means that in the database, review_round_files table during upgrade has values in submission_file_id that don’t correspond to the values in submission_files table, submission_file_id column.
This should be fixed as part of this issue: Foreign key constraint error during upgrade in review_round_files.submission_file_id · Issue #6337 · pkp/pkp-lib · GitHub, so I’m not sure why the error occurs in your case. Can you follow the debugging procedure there and look at the partially updated database for those values:
SELECT submission_file_id FROM review_round_files LEFT JOIN submission_files USING (submission_file_id) WHERE submission_files.submission_file_id IS NULL