why would my OneDrive suddenly be processing over 40,000 changes?

Just happened to me too. Nothing changed, and it's processing over 400k files, slowing down access to the drive.

Just happened to me on a windows 11 computer and a windows 10 laptop. I've reported a bug using the feedback hub. Not holding out much hope of an explanation.

Same issue here. June 2025

Suddenly syncing >200'000 files. Nothing has been changed over the weekend and now any new files or changes aren't syncing?

None of the provided solutions have worked.

This on top of shared folder functionality dropping at random to URL shortcuts.

What is going on? What is the fix? When will it be handled?

has Microsoft offered any explanation and remedy?

Also same problem as well processing nearly 300 000 changes, difficulties synching to various computers, makes working with my assistant almost impossible....

been goingo on for 3 days now and still not finished!

Adding info that might help someone in the future get to the bottom of what is causing this:

I use "Obsidian.md" for note taking. I use a third party plugin with the program that syncs my "Vault" directly with OneDrive. There is a built in feature in this plugin that warns you when a sync attempt would replace/remove/edit >50% of all files, the goal of the feature being to avoid syncing an accidental deletion of many files at once. For reference, the saving situation includes a local (non-OneDrive) "Vault" folder that updates in real time as you edit while the sync plugin creates a separate folder in your OneDrive that updates when you manually ask to sync your local files to the cloud files.

When I attempted to sync my Obsidian files to OneDrive after both instances of OneDrive trying to process 40,000+ files, Obsidian warned me that 100% of the files I was trying to sync were different than the ones already saved in OneDrive. Now, my files were unchanged (to my eye) when I did allow the sync and I did not have any problems, but such a warning suggests that when OneDrive is "processing" the 40,000+ changes, it actually is processing ""changes.""

I do not know much at all about technology and have no clue what that could mean on the technical side, but because this thread is full of other comments about this I thought it would be smart to add in info that could help the smarter people figure out what's going on.

Edit: In terms of what worked for me when I encountered this problem twice, I had to unlink and relink my desktop from OneDrive and allow it to go through the motions of syncing all files after I relinked the account.