Did you follow the directions at
https://www.ubbcentral.com/support/docs/ubbclassic/UBB6_upgrade_within_6.html When you look at step 6 it says
Examine the contents of the 'variables' directory in the upgrade zip. Compare its contents with the variables files you already have on your server. If there are any files that exist in the 'variables' directory of the zip that do not exist on your server, transfer them using ASCII or TEXT mode. Be sure to set permissions, if required.
I would say that the directions are pretty accurate there.
