An increasing number of users can no longer connect with WinCC Viewer RT, even though it used to work for them. Running the application as an administrator still works. On our TSE (so same program), the issue affects some users but not others. For one affected user, deleting and re‑creating their Windows profile resolved the problem. Because the issue appears to be user‑specific, I tried clearing AppData\LocalLow and removing the HKEY_CURRENT_USER\Software\Siemens registry entries, but that didn’t help.

Are there additional files to delete or another fix I can try? I’d rather avoid recreating every affected user’s Windows profile.

WinCCViewer RT version: V08.00.00.05 01.20.00.06 (downloaded for the Wincc V8 server)

Did you make some Windows or WinCC Updates?

Does it work, if the user starts it “as admin” - right click + start as admin

Can you try to just reinstall the ViewerRT before deleting stuff in the user profile folder

I tried what’s relevant in the FAQ (except for section 4.3.3 "Customize Registry" — I haven’t tried that yet).
I didn’t update WinCC.

It works for some users but not for others on the same TSE (so the same program).
It seems to be user-related. Deleting and recreating the Windows session resolves the issue, so it doesn’t appear to be a permissions problem.