OneDrive suddenly stops syncing whenever FSX starts after years of working correctly Post:

Temporarily direct FSXAutosave to a folder outside OneDrive; if OneDrive remains active while FSX runs, the problem is isolated to an autosave file or temporary file that FSX/FSXAutosave keeps open in the synchronized folder.

1. Run a controlled isolation test

1. Close FSX and FSXAutosave.
2. Create a local test folder outside all OneDrive-backed locations, for example:

      C:\FSXAutosave-Test
   

   Do not place it under a OneDrive-backed Desktop or Documents folder.
3. Change only the FSXAutosave output location to that folder.
4. Start OneDrive and wait until its Activity Center reports that syncing is current.
5. Start FSX and trigger at least one autosave.
6. Check whether:
   • the whole OneDrive client pauses or stops;
   • only the original autosave folder remains pending; or
   • OneDrive continues normally.

Microsoft documents that a file being used by another application cannot sync while it remains open. OneDrive should normally sync it after the application saves and closes it.[^1^](https://support.microsoft.com/en-us/onedrive/troubleshoot-onedrive-error-this-file-can-t-be-synced "Troubleshoot OneDrive error: "This file can’t be synced"")

If the test succeeds, keep the active autosave directory outside OneDrive and copy completed saves into OneDrive after FSX closes. This avoids synchronizing files that may be repeatedly rewritten or held open.

2. Identify exactly what is stopping

Immediately after reproducing the issue:

1. Select the OneDrive cloud icon in the notification area.
2. Capture:
   • the complete status or error text;
   • the icon shown;
   • every file listed as open, pending, or recently synchronized;
   • the time to the nearest minute.
3. Check whether the icon actually shows the paused symbol. That symbol specifically means syncing is paused; warning, error, signed-out, and processing icons represent different states.^2^

If the status is Processing changes, Microsoft lists an open file, temporary/hidden files, a large queue, a recent sign-in, or a recent update among the applicable conditions. The Activity Center is where open or recently processed files should be identified.[^3^](https://support.microsoft.com/onedrive/troubleshoot-onedrive-sync-issues-stuck-on-processing-changes#how-to-fix-onedrive-sync-stuck-on-processing-changes "Troubleshoot OneDrive Sync Issues: Stuck on "Processing Changes" | Microsoft Support")

3. Check for an FSX or FSXAutosave file handle

Use Microsoft Sysinternals Process Explorer:

1. Start FSX and reproduce the OneDrive failure.
2. Run Process Explorer as administrator.
3. Select Find → Find Handle or DLL.
4. Search first for the autosave filename, then for part of its folder path.
5. Record the process name and path returned—particularly whether it is FSX, FSXAutosave, another add-on, antivirus software, or another process.

Process Explorer is designed to search which processes have particular files or directories open.^4^

Do not forcibly close a handle from Process Explorer; that can corrupt an in-progress save. Close the owning application normally or change its output location.

Could an update be responsible?

A recent update is possible, but the available Microsoft release information does not establish a known FSX-specific OneDrive issue. OneDrive releases roll out gradually, so correlate the installed build rather than assuming every computer received the same version simultaneously.^5^

Record:

• OneDrive version: OneDrive cloud icon → Help & Settings → Settings → About.
• Windows build: press Windows+R, enter winver, and capture the displayed version.
• Update date: Settings → Windows Update → Update history.
• The last date this workflow definitely succeeded.

Avoid uninstalling a security update until the isolation and handle tests are complete.

If no file handle or path dependency is found

Reset OneDrive only after capturing the evidence above. A reset does not delete the files, but it resets OneDrive settings, disconnects sync connections, and causes a full synchronization.^6^

1. Close FSX.
2. Press Windows+R and run:

      %localappdata%\Microsoft\OneDrive\onedrive.exe /reset
   

3. If Windows cannot find it, run:

      C:\Program Files\Microsoft OneDrive\onedrive.exe /reset
   

4. Open Start, search for OneDrive, and start it manually.
5. Wait for the full synchronization to finish, then repeat the outside-OneDrive test.

If the issue remains, submit the exact timestamps, screenshots, OneDrive and Windows versions, affected paths, Process Explorer results, and both isolation-test outcomes through Contact Microsoft Support for a personal account or through the organization’s help desk for a work/school account.^7^

References

1. Troubleshoot OneDrive error: "This file can’t be synced"
2. [Windows](https://support.microsoft.com/onedrive/what-do-the-onedrive-icons-mean)
3. Troubleshoot OneDrive Sync Issues: Stuck on "Processing Changes" | Microsoft Support
4. Process Explorer v17.2
5. OneDrive Sync release notes - SharePoint in Microsoft 365
6. Reset OneDrive | Microsoft Support
7. Fix OneDrive sync problems | Microsoft Support