I work in a Windows environment. As part of that, there is OneDrive.

At some point, OneDrive basically ceased to function. I learned a few things and will share them here.

First, from this support page, I learned that:

For optimum performance, we recommend syncing no more than a total of 300,000 items across your cloud storage. Performance issues can occur if you have more than 300,000 items, even if you are not syncing all items.

I had close to double that. Of course, no warning or message from OneDrive itself.

I did total and complete uninstall and reinstalls, removing existing files.

When I reinstalled, I was still get a mysterious ‘downloading, 3 files and 0 kB remaining’ message at the top that would never go away.

How did I solve this one? Here was my process, which may help debug other issues.

  1. Quit OneDrive
  2. Copy the database file storing the sync information at %LOCALAPPDATA%\Microsoft\OneDrive\settings\Business1\SyncEngineDatabase.db (or Personal instead of Business1).
  3. Turn your OneDrive back on
  4. Make sure you have sqlite3 CLI installed
  5. Go to your favorite very smart Ph.D. level intelligence LLM and tell it your situation
  6. Wait as it analyzes your database and tells you which files are the problem

For me, the issue was long file lengths on OneDrive coming from an automated process (Power Automate) that was directly pushing items into the OneDrive.

Of course, no message or log from OneDrive itself telling me that was the issue.