After updating OneDrive and applying the September cumulative updates in our Windows Server 2019 RDS farm, the OneDrive tray interface stopped opening on versions newer than 26.139.0720.0007 from August 7, 2026. Syncing still works for users who were already signed in, but launching OneDrive only shows a small centered window with an X, and choosing Sign in from the tray does nothing. The issue also occurs on hosts that have not received the September updates yet. The RDP problem was resolved by installing the September hotpatch, but the OneDrive GUI issue remains. Setting DisableFileSyncNGSC to 0 and running a OneDrive reset did not help. Rolling back to version 26.139.0720.0007 is currently the only workaround. Has anyone found other troubleshooting steps or a fix?
3 Answers
Since the problem is also present on hosts that missed the September patches, I would avoid assuming the cumulative update is the sole cause. Capture the sign-in attempt on a working system and an RDS host, then compare process creation, registry access, file access, and network activity. Differences in user-session permissions, security policy, WebView2 initialization, or application control rules may reveal why the GUI fails while background syncing continues.
Compare a working machine running the new build with one of the affected RDS hosts. The sign-in window depends on the WebView2 Runtime, so verify that WebView2 is installed and current, and check whether msedgewebview2.exe launches in the affected user's session when the tray icon is clicked. Also review AppLocker and WDAC logs for blocks involving the per-machine OneDrive installation directory or WebView2 files.
I would start by checking the event logs, especially application errors and security-related logs. A similar issue can happen when an application starts requiring a newer Microsoft C++ runtime that is missing from the host. That said, if OneDrive continues syncing and there are no corresponding events, the failure may be limited to the sign-in UI rather than the sync engine.
There is nothing useful in the event logs so far. OneDrive syncs files normally, but the tray menu and sign-in window never appear.