Server side:
A) Switch "Interactive User" to "This User".
B) "This User" only works after creating these folders :
- C:\Windows\SysWOW64\config\systemprofile\Desktop
- C:\Windows\System32\config\systemprofile\Desktop
C) Wait for it... Step B) triggers Windows to auto create:
Note the definition of "Interactive User" is to piggybacked on whatever is the active logged in user to the server. Thus failure to launch MS Office when no user is active on the server.
I.e., for me, the solution was a hybrid of the already proposed solutions. I used Office 2013 (x86) on Win 2012R2. My issue was instead with Word (to use WordToPDF).
Details for Step B:
- Login to Server > Start > run DCOMCNFG.EXE (to launch Component Services) > Console Root > Component Services > Computers > My Computer > DCOM Config...
- Scroll to “Microsoft Word 97 - 2003 Document” or "Microsoft Excel Application" (... i.e., whatever MS Office thing you need to launch)...
- Right click it and select “properties” > Identity tab > Choose “This User” > enter credentials for some user with access to MS Office on the server. (I used a user with administrator permissions.)
Details for Step C:
- The wait varies from 5 min to over-night. Optionally, create this folder manually (if the folder does not exist and you're in a rush to complete testing).