Microsoft Teams uses OneDrive behind the scenes to store and share any file you attach in a chat or channel — even though it doesn't always look that way from the chat window. When that connection breaks, file uploads fail with the error "Unable to connect to OneDrive. Please try uploading again." Here's what typically causes it and how to fix it.
Common causes
- OneDrive storage is full. If your OneDrive has hit its storage limit, Teams can't upload new files through it, since there's nowhere for the file to actually land.
- Outdated Teams app. An older version of Teams can have compatibility issues with current OneDrive APIs.
- Corrupted local cache. Teams keeps a local cache that can occasionally become corrupted, breaking the OneDrive connection specifically.
- Renamed default document library. In organizational/work accounts, if an admin renamed the default "Documents" library in SharePoint or OneDrive, Teams can fail to find the expected upload destination.
- Restricted permissions. If your account has restricted access to OneDrive folders (common in tightly-locked-down organizational accounts), uploads can fail silently with this generic error.
Fix 1: Check your OneDrive storage
- Go to onedrive.com and sign in
- Check your storage usage, usually visible in the bottom-left of the sidebar
- If you're at or near your limit, delete files you don't need, move large files to local/external storage, or upgrade your storage plan if this is a recurring problem
Fix 2: Update Teams
- Open Teams
- Click your profile picture in the top right
- Select Check for updates
- Let it install any available update, then restart Teams
Fix 3: Clear the Teams cache
This resolves a surprising number of odd, hard-to-explain Teams glitches, not just this one:
- Fully close Teams (check Task Manager to confirm no Teams process is still running in the background)
- Press Windows key + R, type
%appdata%\Microsoft\Teams, and press Enter - Delete the contents of this folder (or the whole folder — Teams will recreate what it needs on next launch)
- Reopen Teams and sign back in
Note for the new Teams client: if you're on the newer Teams app (rebuilt architecture, rolled out as the default since 2023), the cache location differs slightly — try %localappdata%\Packages\MSTeams_8wekyb3d8bbwe\LocalCache instead if the path above doesn't exist on your system.
Fix 4: Check with IT if you're on a managed work account
If you're on a company-managed Microsoft 365 account and the above steps don't help, this may be a permissions or configuration issue on the organization's side rather than something fixable from your end — for example, a renamed default document library, which only an admin can correct via the Microsoft 365 Admin Center. Worth flagging to IT with the exact error message if personal troubleshooting doesn't resolve it.