It should be noted that incase there are more than one UAG server in the array, this change should be applied on all servers manually by the same method and steps above.
After the install of UAG 2010 SP3, all of the portal applications worked fine except for the File Access application. I tried several options with the application, removing it and adding it back but never worked till I asked my friend Ben Ari (UAG Senior Escalation engineer) as I thought it was depreciated. It turned out to be a glitch or bug after implementing the UAG 2010 SP3 and to fix you need to do the following:
1. On the UAG server, Navigate to the following folder under UAG installation folder Microsoft Forefront Unified Access GatewayvonFileAccess
2. Edit the file “default.asp” (I took a backup first before any change)
3. Modify the word cint to parseInt on Line 20 (Or you can search the file as it appears once). Make sure that the “I” in “parseInt” is written in caps (Check below screenshot)
4. Save and activate your Forefront UAG