Upgrade Company file from v19 to 2016.1 fails with error Inserting Constraints: A foreign key value cannot be inserted because a corresponding primary key value does not exist.

Have optimised and verified the file, but after trying 3 times to upgrade file, I'm at a loss.

I tried to do the upgrade on-line (although we must run the file locally), but the web complains about the serial numbers being incorrect, even though they are identical.

Any idea's 

Craig