OneDrive sync issues with SharePoint libraries
OneDrive stops or slows syncing a SharePoint library when something hits a documented limit: too many items across the storage you sync, a file name or path the service rejects, a file over the size limit, a library set to require checkout or validation, or a full storage quota. Most sync problems on SharePoint libraries trace back to one of these, so the quickest fix is usually to identify which one applies before you reset anything.
This page lists each limit with the figure Microsoft publishes, then the steps to try in order when a library will not sync.
The limits that cause sync problems
| What goes wrong | The limit or rule | What to do |
|---|---|---|
| Sync is slow or stalls on a large library | Microsoft recommends syncing no more than 300,000 items in total across your cloud storage. Performance issues can occur above that, even if you are not syncing every item. | Choose which folders each device syncs so the total stays below the recommendation. |
| A file will not sync | These characters are not allowed in names: " * : < > ? / \ |. Leading and trailing spaces are not allowed either. | Rename the file or folder. |
| A file will not sync | Restricted names: .lock, CON, PRN, AUX, NUL, COM0 to COM9, LPT0 to LPT9, _vti_, desktop.ini, and any name starting with ~$. | Rename it. |
| A file will not sync | Temporary TMP files do not sync, and administrators can block specific file types from syncing. | Check with your administrator. |
| A deep folder structure fails | The decoded file path, folder path and file name combined, is limited to 400 characters in SharePoint Online. | Shorten folder or file names, or move the files closer to the library root. |
| A very large file will not sync | The file size limit is 250 GB. For any file larger than a few GB, use the sync app instead of the website upload. | Split or compress the file. |
| A library syncs as read-only | Libraries with checkout, validation or restricted draft settings sync as read-only. Read and write access needs Contribute permission or higher. | Change the library setting or the permission. |
| New files will not upload, edit or sync | When storage is full, Microsoft blocks new uploads, edits and syncing, and existing files become read-only. | Free space or add storage. |
Microsoft's list of SharePoint Online limits has the full set, and every SharePoint Online limit summarizes them in one place.
Setups the sync app does not support
- A network or mapped drive as the sync location.
- Running OneDrive with elevated privileges.
- Authenticated proxies.
- Roaming, mandatory and temporary Windows profiles.
- Symbolic links and junction points.
- More than one OneDrive for home account and nine OneDrive for work or school accounts on one device.
Steps to try, in order
- Read the icon. The OneDrive icon in the taskbar or menu bar shows states such as sync error, paused, account nearly full, account full, locked or frozen, and file locked. Select it to see which files are affected.
- Check the table above for a name, path, size, permission or storage cause. Fixing the cause is usually enough.
- Unlink and relink the account. Microsoft suggests this when problems continue.
- Reset OneDrive. On Windows, press the Windows key and R, then run
%localappdata%\Microsoft\OneDrive\onedrive.exe /reset. If Windows cannot find the file, run the same command from the OneDrive folder under Program Files. Microsoft's community answer describes the reset as clearing the OneDrive settings and starting a full sync afterwards, so allow time on a large library. - Contact your administrator on a work or school account. Microsoft directs users to their organization's IT help desk, and administrators to the OneDrive admin help.
Tenant storage and synced libraries
When a tenant is over its SharePoint quota, its sites become read-only, and libraries stop accepting uploads and edits. SharePoint sites read-only because storage is full lists the messages and what to do first.
Free storage so sync keeps working
A full tenant is the one cause on this page that stops every library at once. Squirrel archives inactive files from SharePoint document libraries into Azure Blob Storage in your own subscription and leaves a stub with the original name, which frees SharePoint storage while a user still restores a file in one click. Stubs work in OneDrive-synced folders, so people keep the same view they have today. SharePoint slow with large document libraries covers the Microsoft limits behind slow libraries and what archiving changes.
Frequently asked questions
How many files can OneDrive sync from SharePoint?
Microsoft recommends syncing no more than a total of 300,000 items across your cloud storage, and performance issues can occur above that even if you do not sync every item.
What characters stop a file syncing to OneDrive?
The characters " * : < > ? / \ | are not allowed in names, and neither are leading or trailing spaces. Names starting with ~$ and the names .lock, CON, PRN, AUX, NUL, COM0 to COM9, LPT0 to LPT9, _vti_ and desktop.ini are restricted.
What is the maximum file size for OneDrive and SharePoint?
250 GB for an individual file. For anything larger than a few GB, use the OneDrive sync app instead of uploading through the website.
What is the maximum path length for a SharePoint file?
400 characters for the decoded path, which is the folder path and the file name combined.
Why is my SharePoint library read-only in File Explorer?
Libraries with checkout, validation or restricted draft settings sync as read-only. Read and write access needs Contribute permission or higher.
How do I reset OneDrive?
On Windows, press the Windows key and R, and run %localappdata%\Microsoft\OneDrive\onedrive.exe /reset. A full sync follows.
Related reading
- Every SharePoint Online limit - the limits that cause sync and storage problems, in one table.
- SharePoint sites read-only because storage is full - what to do when a tenant is over quota.
- SharePoint slow with large document libraries - thresholds, fixes and what archiving changes.
- OneDrive deleted files: how to recover them - restoring files deleted from a synced folder.
- SharePoint Storage Explorer - free tool that reports storage by site, library and file.
Mark Smith co-founded SmiKar Software in 2015 and has spent the past decade helping organisations solve Microsoft 365 data management challenges. He works with the SmiKar team to build solutions for SharePoint archiving, storage optimisation, governance and compliance, supporting customers from growing businesses through to Fortune 500 enterprises.
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