When you migrate files from an on-premises file server to OneDrive, remote users often report missing files. This happens because the migration tool copies files from the server while remote users are disconnected from the corporate VPN or network. The root cause is that the migration tool only sees the files present on the server at the moment of scanning, but remote users may have pending offline changes or cached versions that differ from the server copy. This article explains the specific causes of missing files during a file server migration and provides a step-by-step checklist for administrators to ensure all files are captured for remote users.
Key Takeaways: File Server Migration Checklist for Remote Users
- Migration tool scan settings: Set the tool to scan file servers during business hours when remote users are actively connected to the VPN to capture all active files.
- Offline Files cache sync: Instruct remote users to sync their Offline Files cache before the migration cutover to upload pending changes to the server.
- OneDrive Known Folder Move: Redirect remote users’ Desktop, Documents, and Pictures folders to OneDrive before the migration to avoid file duplication.
Why File Server Migrations Miss Files for Remote Users
File server migration tools such as Microsoft’s SharePoint Migration Tool or third-party tools like Quest or Mover copy files from the source server to the destination OneDrive or SharePoint site. These tools scan the file server at a specific point in time. If a remote user has files stored locally in their Offline Files cache that have not been synced back to the server, those files are not visible to the migration tool. The tool then skips those files, causing them to be missing from the destination.
Another common scenario occurs when remote users work on files stored on a mapped network drive that is only accessible when connected to the corporate VPN. If the user disconnects from the VPN while the migration is running, the file server may show a stale version of those files. The migration tool copies the stale version, and the user’s latest changes are lost or overwritten.
A third cause is that remote users may have files in their local folder that are not on the network drive at all. For example, a user might save a file to their local Desktop instead of the network drive. The migration tool never sees that local file, so it is not migrated.
Checklist: Ensure All Remote User Files Are Migrated
Follow this checklist in order to minimize missing files for remote users during a file server migration to OneDrive.
- Audit remote user connectivity and Offline Files settings
Before the migration, identify all users who work remotely. Check their Group Policy or local settings for Offline Files. Ensure Offline Files is enabled and configured to sync files from the network drive. Confirm that the Offline Files cache size is set to at least 10 GB or more depending on the user’s workload. - Require remote users to sync Offline Files before cutover
Send an email to all remote users with instructions to connect to the VPN and open the Offline Files sync center. Tell them to click Sync All to upload any pending changes to the file server. This step must be completed at least 24 hours before the migration tool scans the server. - Schedule the migration scan during business hours
Configure the migration tool to scan the file server between 9 AM and 5 PM local time when remote users are most likely connected to the VPN. Avoid scanning during weekends or holidays when remote users are typically offline. - Enable Known Folder Move for remote users before migration
If remote users store files on their local Desktop or Documents folder, redirect those folders to OneDrive using Known Folder Move. This ensures those files are synced to the cloud and included in the migration destination. Go to the Microsoft 365 admin center, navigate to OneDrive > Sync, and enable Known Folder Move for all users. - Run a pre-migration file inventory report
Use the migration tool’s reporting feature to generate a list of all files on the file server. Compare this list with a list of files that remote users report having. If the server list is missing files, ask the user to sync Offline Files again and re-run the inventory. - Perform a test migration with a pilot group
Select 5 to 10 remote users for a pilot migration. Run the migration tool on their file shares. After the migration completes, ask the pilot users to verify that all their files appear in OneDrive. If they find missing files, troubleshoot the Offline Files sync and retry. - Use the migration tool’s incremental copy feature
Most migration tools support incremental copies that only transfer new or changed files. After the initial full scan, schedule an incremental copy 24 hours later. This captures any files that were synced by remote users after the initial scan. - Document the migration cutover window and communicate it
Set a specific cutover time when the file server will be read-only or taken offline. Communicate this time to all remote users at least one week in advance. Ask them to complete all file saves and sync Offline Files 30 minutes before the cutover. - Verify OneDrive sync status for each remote user post-migration
After migration, check the OneDrive sync client status on each remote user’s device. Look for sync errors, conflicts, or files that show a red X. Use the OneDrive Support tool to run the Sync Troubleshooter if needed. - Retain a backup of the file server for 30 days post-migration
Keep the original file server available in read-only mode for 30 days after the migration. This allows remote users to manually copy any files that were missed. After 30 days, take the server offline.
If Files Are Still Missing After the Migration
Remote user says a file was saved locally but not on the server
Ask the user to check their local Offline Files cache. Open Control Panel > Sync Center > Manage offline files. Click View your offline files. If the file exists there, copy it to the network drive and sync it. Then run a manual upload to the OneDrive destination using the OneDrive web interface.
Migration tool shows the file was copied but the user cannot find it in OneDrive
The file may have been placed in a different OneDrive folder due to a path mapping error. Check the migration tool’s log files for the exact destination path. Ask the user to search for the file name in OneDrive.com using the search bar. If the file is found, note the folder path and instruct the user to move it to the correct location.
User had multiple versions of the same file and the wrong version was migrated
This occurs when the file server had an older version due to a sync delay. Use the migration tool’s version history feature if available. Alternatively, restore the file from the file server backup taken before the migration. Then ask the user to upload the correct version manually to OneDrive.
File Server Migration vs OneDrive Sync: Key Differences for Remote Users
| Item | File Server Migration | OneDrive Sync |
|---|---|---|
| Data source | On-premises file server | Cloud-based OneDrive storage |
| Access method | Mapped network drive via VPN or LAN | OneDrive sync client or web browser |
| Offline file handling | Offline Files cache on Windows; sync required before migration | Files On-Demand; no manual sync needed |
| File version conflicts | Older version on server may be copied; no conflict detection | Built-in conflict resolution with version history |
| Remote user impact | Must sync Offline Files and connect to VPN before cutover | No VPN needed; files sync automatically when online |
File server migrations require more manual coordination with remote users compared to the always-on sync behavior of OneDrive. The migration process is a one-time event, while OneDrive sync is continuous.
After following this checklist, remote users should have all their files available in OneDrive. The most critical step is to enforce Offline Files sync before the migration scan. For future migrations, consider using OneDrive Known Folder Move to eliminate the dependency on network drives entirely. An advanced tip: use the migration tool’s PowerShell cmdlets to automate the pre-migration file inventory and compare it with a list of files from each user’s Offline Files cache.