Cannot get into routings, error comes up as cannot open file C:\DBAMFG\UDF6.src.
This is our first time getting into these files since our last update.
Version 2015.2, Build 7/02/15 T7-7i R6

You need to go to Queries - SU-A, bring up the ROAROUTING grid and delete any references to UDF

I'm afraid I can't tell you what to do to fix your problem, but I am quite certain that all your routings are still there.  
 
To be sure, you could create a new WO, then go to WO Routings (sorry - can't remember the menu location, it's Ctrl-Y on our system...) and see if there is a routing on the WO. If there is, the routings are actually still there. You could also use Maintain Database on ROUTING.B?? (where ?? is your company extension) and you should see all your Routings there, albeit in a not-so-easy-to-read format.
 
To encourage you until you figure this out, here's what I suggest.
 
Go to UT-A, type in BKROA and press Enter. You will have the legacy/old-fashioned Routings screen, and I would bet you will find all your items' routings there. You can use BKROA with no penalty or loss of performance until you get this figured out (either from UT-A, or use TAS-G [I think] and replace T7ROA.RWN with BKROA.RUN.
 
My guess is that the Grid Layout is somehow compromised in the T7 version of the application, and you need to somehow restore the original.
 
FWIW, I don't know/can't remember why, but we are not using T7-ROA. We still use the BK version.
 
 
PLEASE NOTE: all the above filename/application/menu details were done from memory. Please verify validity before making any actual changes to your system. I'm just a guy who uses DBA/Evo.

Thank you. Queries - SD - D (there is no E) worked to restore the grid.
Then everything worked fine and I was able to get into all the routings!