OneDrive for Business file server migration troubleshooting for executive data: misses files

When migrating file server data to OneDrive for Business, executive data folders sometimes arrive with missing files. This problem occurs when the migration tool skips files that exceed path length limits, have unsupported characters, or are locked by open applications. This article explains why files go missing during migration and provides step-by-step methods to locate and recover them.

Why Files Go Missing During File Server Migration to OneDrive

The core cause is that file server data often contains file paths longer than 260 characters, which is the maximum path length supported by the Windows 10 file system. When the SharePoint Migration Tool or any other migration agent encounters a file path exceeding this limit, it skips the file without moving it and does not report the skip by default. Additionally, files with reserved characters such as ~ " # % & : < > ? / \ { | } in their names are also skipped. Executive data folders tend to have deeply nested subfolders and long descriptive filenames, making them especially prone to these path length violations. Another common cause is that files are locked by an open application on the source server during the migration window, causing the tool to treat them as inaccessible and skip them.

Path Length Limits in Windows 10 and OneDrive

Windows 10 has a legacy MAX_PATH limit of 260 characters for file paths. This limit applies to the full path including the drive letter, folder names, and the file name. OneDrive for Business synchronizes files using the Windows file system, so any file with a path longer than 260 characters cannot be stored or synced. When migrating from a file server, the migration tool checks the path length before copying. If the path exceeds the limit, the file is omitted from the migration output.

Unsupported Characters and File Types

The SharePoint Migration Tool blocks files whose names contain characters that are not allowed in OneDrive or SharePoint. These include ~ " # % & : < > ? / \ { | }. Files with names ending in a period or a space are also skipped. Executive data folders sometimes contain files with these characters because the file server file system allows them. The migration tool logs these skips but does not display them in the default summary view.

File Locking During Migration

If a file is open in an application such as Microsoft Excel or Adobe Acrobat on the source server at the time the migration tool tries to read it, the tool cannot access the file. The tool treats the file as unavailable and proceeds to the next item. This is a transient condition: if the file is closed before the next scan pass, it will be included. However, in a single-pass migration, locked files are permanently missed.

Steps to Find and Recover Missing Files After Migration

Use the following procedure to identify every skipped file and then migrate it correctly.

1. Run the SharePoint Migration Tool scan report
   Open the SharePoint Migration Tool (SPMT) on the machine that performed the migration. Click the Reports tab. Select the migration job that processed the executive data folder. Click Download scan report. The report is a CSV file that lists every file the tool evaluated. Look for the Status column. Any row with a status other than Success indicates a skipped file. The Error Message column describes the reason.
2. Identify files with path length issues
   In the CSV report, filter the Source Path column for paths longer than 260 characters. You can use Excel or a text editor with a character count function. For each file, note the full source path. These files must be either renamed to shorten the total path or moved to a shallower folder structure on the source server before you can migrate them.
3. Rename or move files to shorten paths
   On the file server, navigate to each file identified in step 2. Rename the file to a shorter name, or move the file to a parent folder that is closer to the root. Ensure the new path is under 260 characters. After making the change, run a new SPMT scan on that folder only. The file should now appear with a status of Ready.
4. Remove unsupported characters from file names
   For files whose error message mentions unsupported characters, rename the file on the source server to remove or replace the character. For example, replace # with No and & with and. Avoid using periods in the middle of a file name. After renaming, rescan the folder with SPMT.
5. Enable long path support in Windows 10
   On the machine that runs the migration tool, you can enable long path support by modifying the Group Policy. Open the Local Group Policy Editor. Navigate to Computer Configuration > Administrative Templates > System > Filesystem. Enable the policy Enable Win32 long paths. Restart the machine. This allows SPMT to handle paths up to 32,767 characters. Note that OneDrive for Business itself still enforces the 260-character limit for synced files, so this only helps during the migration step.
6. Check for locked files and schedule a second pass
   Ask the executive users to close all files on the file server during the migration window. Alternatively, schedule the migration to run during off-hours when the files are not in use. After confirming that no files are open, run an incremental migration pass on the same folder. SPMT will compare the source and destination and migrate only the files that are missing.
7. Verify the final file count in OneDrive
   In OneDrive for Business, navigate to the target folder. Right-click the folder and select Properties. Compare the file count with the source folder on the file server. If the numbers match, the migration is complete. If not, repeat steps 1 through 6 for the remaining files.

If Files Are Still Missing After the Main Fix

Even after following the steps above, some files may remain missing due to edge cases that require additional attention.

OneDrive Shows a Red X on Shared Office Files

After migration, some Office files may display a red X in File Explorer. This happens when the file has a co-authoring conflict or a stale lock from the original file server. To fix this, open the file directly from the OneDrive website. Click the file to open it in the Office Online app. Close the file. The red X should disappear within a few minutes as OneDrive syncs the metadata.

Files Are Present in OneDrive but Not in the Local Sync Folder

This occurs when the user has Files On-Demand enabled and the file was not yet downloaded. The file appears as a cloud-only placeholder. To force a download, right-click the file in File Explorer and select Always keep on this device. The file will download to the local hard drive.

Migration Tool Reports Success but Files Are Not in OneDrive

This is caused by a timing issue where the migration tool completes before OneDrive finishes indexing the new files. Wait 15 minutes, then refresh the OneDrive website. If the files still do not appear, check the SharePoint admin center under Active migrations for any stuck jobs. Resume the job from the admin center.

SharePoint Migration Tool vs Manual Copy: Key Differences for Executive Data

Item	SharePoint Migration Tool (SPMT)	Manual Copy via File Explorer
Description	Automated tool that scans, validates, and migrates files with detailed reporting	Drag-and-drop copy using Windows File Explorer or Robocopy
Path length handling	Reports paths over 260 characters and skips them; can be configured to use long paths	Fails silently or truncates file names; no error report
Unsupported characters	Identifies and logs each character violation	Blocks copy with a generic error message
File locking detection	Skips locked files and logs the skip	Fails with an access denied error
Incremental migration	Supports delta scans to catch previously skipped files	Requires manual re-copy of entire folder
Best for	Large executive data sets with complex folder structures	Small folders with simple names and short paths

This table shows that SPMT is the superior choice for executive data because it provides actionable error reports and supports incremental passes. Manual copy is acceptable only for folders with fewer than 100 files and no path length concerns.

You can now locate every missing file from your executive data migration by using the SPMT scan report. After renaming long paths and removing unsupported characters, run an incremental migration to bring the missing files into OneDrive. For future migrations, enable the Win32 long paths policy on the migration machine before starting the scan to reduce the number of skipped files.