I was trying out a backup to OneDrive using Arq5, the backup had got to 400GB (hadn’t noticed it had got that far). I decided to quit the backup and deleted the files created by Arq5 from the web interface of OneDrive.
This is when problems started, the 5 machines that sync OneDrive folders (1 full and 4 on on-demand sync) all went into permanent sync but no new adds or deletes were taking place.
Solution
On each computer, take a note of all the folders selected to sync in the OneDrive client.
Open a Run prompt Win+R paste in:
%localappdata%\Microsoft\OneDrive\onedrive.exe /reset
This will close down OneDrive client, wait a minute, then run:
%localappdata%\Microsoft\OneDrive\onedrive.exe
This will start up the client.
Open the ‘select folders to sync’ dialog and make sure only the folder noted above are ticked, leave it to sync.
If some of the folders that are not selected have started downloading, at the end of the sync these will be indicated with a red cross, and can be deleted if indicated in the ‘View Sync Problems’ list.
Conclusion
I believe that the deleted 400GB in the Arq Backup Data folder, even though not selected to sync with any client, was still in the client file lists, when I deleted them from the web all 5 devices were trying to update their file lists.
After a reset the folders were syncing properly across all 5 devices within an hour, where they had been trying for nearly 2 days before.
