OneDrive appears to have stopped syncing for five days on a user's computer. An Excel file on the desktop lost its formatting, and the latest available version history is from before the apparent outage. The file is a CSV.
What should I check, and is there a way to alert us when OneDrive stops working?
There are two separate problems here. CSV stores plain tabular data, not Excel formatting, so saving as CSV loses the formatting even if OneDrive is working perfectly. Save a formatted workbook as XLSX and use CSV only when you need that format for data exchange.
For recovery, check the local desktop file and any available backups as well as OneDrive version history. A version that was never synced will not be in the cloud history. If no copy retained the formatting, it may have to be recreated.
Start with the OneDrive client on the affected machine. Is it running, signed in, and showing a sync error? Check whether the desktop folder is actually included in OneDrive backup, then compare the local file with the copy online. A sign-in problem or a sync error could leave the client running without current files reaching the cloud.
Don't overwrite either copy while investigating. Preserve what is there first, then work out which version contains the latest data.
If you have endpoint management, a scheduled check for OneDrive running in the signed-in user's session can alert IT or try starting it again. That catches the missing process, which is a useful first step, but it doesn't prove sync is healthy. A running client can still be signed out or stuck on an error.
If you can reliably collect client status, alert on failed sync or sign-in issues too, and send unresolved failures to a central log for someone to review. Test any automatic restart carefully so it doesn't keep interrupting the user or hide a recurring problem.
There's also a OneDrive Sync health dashboard in the Microsoft 365 Apps admin center. Reporting has to be enabled through policy first. It can help find unhealthy clients across the organization, but don't count on it as a real-time alert. Reports can be delayed and may miss some errors, so verify what it catches in your environment.
Show users where to check the OneDrive status and ask them to report sync warnings, but don't make a tiny notification-area icon the only safeguard. For important work, have a backup or other recovery process and a way to escalate a sync failure before it goes unnoticed for days.
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4j+parcelhinge_903:
Checking for no file activity alone could be noisy. A user might simply not have changed any synced files during that period.