[otrs] error during migration to 3.1

Hi all, I'm getting this during DBUpdate-to-3.1.pl Migrated 0 articles of 0. done. A field was not correctly migrated: 14 Ticket 873 Found DynamicField value '', expected ''! Step 7 of 22: Verify if ticket data was successfully migrated... done. Some hints on what I have to search in db data ?