Looking at the error, I tryed to extract from publication_formats values with submission_id = NULL
Then I deleted the result records:
SELECT pf.publication_format_id FROM publication_formats pf LEFT JOIN submissions s ON (pf.submissioion_id = s.submission_id) WHERE s.submission_id IS NULL;
DELETE FROM publication_formats pf WHERE pf.publication_format_id = (int);
So it worked!!! I sucessfully upgraded to 3.2.0.
Now starts the climb to the 3.3