OneDrive KFM Fails Because Desktop Contains Unsupported Files

When you enable Known Folder Move in OneDrive, the sync may fail or stop with an error if your Desktop folder contains files that OneDrive cannot sync. Unsupported file types such as .lnk shortcuts, .tmp temporary files, or files with blocked extensions prevent the KFM setup from completing. This article explains which files cause the failure, why OneDrive blocks them, and how to remove or relocate those files so KFM can finish successfully.

Why OneDrive Blocks Certain Files During Known Folder Move

OneDrive enforces file-type restrictions during Known Folder Move to prevent sync errors, security risks, and performance degradation. The Desktop folder is a common location for shortcuts, temporary installers, and system-generated files that OneDrive cannot sync. When KFM attempts to move the Desktop folder to OneDrive, it scans every file. If it finds any file with an unsupported extension, the entire KFM process stops and shows an error such as “We can’t move your folder because it contains files that can’t be synced.”

The blocked file types include:

• Shortcut files: .lnk (Windows shortcuts), .url (internet shortcuts)
• Temporary files: .tmp, .temp, .~ (tilde-prefixed backup files)
• System files: .ini, .log, .dll, .exe, .msi
• OneDrive internal files: .one, .onetoc2 (OneNote files are allowed, but certain metadata files are blocked)
• Files with blocked extensions: Administrators can block additional extensions via group policy or SharePoint admin center

OneDrive also blocks files with names longer than 400 characters, files with reserved Windows names like CON, PRN, AUX, and files with trailing periods or spaces. If your Desktop contains any of these, KFM will fail.

Steps to Remove Unsupported Files and Complete KFM

Follow these steps to identify and remove the files blocking Known Folder Move, then retry the setup.

1. Identify the blocking files using the OneDrive error message
   Open OneDrive and click the OneDrive icon in the notification area. If KFM failed, a notification appears. Click the notification to open the Sync and backup settings. The error message lists the file types that are blocked. Write down the extensions mentioned.
2. Open the Desktop folder in File Explorer
   Press Win + E to open File Explorer. In the left pane, click Desktop. This shows all files and folders currently on your Desktop.
3. Sort files by type to find blocked extensions
   Click the Type column header in File Explorer to group files by extension. Look for files with extensions like .lnk, .tmp, .url, .exe, .msi, .ini, or any extension mentioned in the OneDrive error. Do not delete files you need — move them instead.
4. Move unsupported files to a different location
   Select each blocked file, press Ctrl + X to cut, then navigate to a folder outside of OneDrive, such as Documents > TempFiles or C:\Users\YourName\DesktopBackup. Press Ctrl + V to paste. Do not use the OneDrive folder as the destination.
5. Delete temporary files that are safe to remove
   For .tmp files, .log files, and other temporary data that you do not need, select them and press Shift + Delete to permanently remove them. Empty the Recycle Bin afterward to ensure OneDrive does not scan them again.
6. Retry Known Folder Move
   Open OneDrive settings again. Go to Sync and backup > Manage backup. Click Update next to Desktop. OneDrive will scan the folder again. If no blocked files remain, the move will complete.
7. Enable Files On-Demand before retrying (recommended)
   In OneDrive settings, go to Sync and backup > Advanced settings > Files On-Demand. Toggle Files On-Demand to On. This reduces the amount of local storage used during the sync and prevents conflicts with large files.

If OneDrive Still Reports Blocked Files After Cleanup

OneDrive says “We can’t move your folder” but you removed all visible blocked files

OneDrive may detect hidden files or system files that are not visible in File Explorer by default. To see these files, open File Explorer, click the View tab, then check Hidden items. Also uncheck Hide protected operating system files in the Folder Options. Look for files with names starting with a tilde (~), such as ~$temp.docx, or files named thumbs.db. Move or delete these files, then retry KFM.

OneDrive fails on Desktop but no error message appears

Open OneDrive settings and go to Sync and backup > Manage backup. If the Desktop status shows “Not backed up” or “Error,” click Update. OneDrive will scan again and display a specific error if blocked files remain. If no error appears, the issue may be a network or permissions problem. Check that your account has write access to the OneDrive folder and that your internet connection is stable.

KFM fails because of OneDrive sync limits

OneDrive cannot sync more than 300,000 files across all synced folders. If your Desktop contains a large number of files, even if all are supported, KFM may fail. Reduce the file count by moving old files to an archive folder outside the Desktop. After reducing the count, retry KFM.

Known Folder Move vs Manual Desktop Sync: Key Differences

Item	Known Folder Move (KFM)	Manual Desktop Sync
Setup method	OneDrive settings > Sync and backup > Manage backup	Right-click Desktop folder > Properties > Location > Move to OneDrive folder
File type restrictions	Blocks unsupported files during setup; requires cleanup before proceeding	No block during setup; unsupported files cause sync errors after move
Error handling	Stops the entire move if one unsupported file is found	Syncs supported files; unsupported files remain local with sync errors
Group policy support	Controlled via Microsoft 365 admin center and group policy	Not centrally managed; user-driven
Best for	Enterprise deployments requiring centralized backup of Desktop, Documents, and Pictures	Individual users who want to sync Desktop without IT policy restrictions

Known Folder Move provides a managed, policy-controlled way to back up the Desktop folder. Manual sync gives more flexibility but lacks the error prevention that KFM offers. If you frequently encounter unsupported files, use KFM with the cleanup steps above to avoid repeated failures.