OneDrive Admin Checklist: file server migration breaks recent links for mergers

After your organization completes a merger or acquisition, migrating file servers to a new environment often breaks recently shared OneDrive links. Users receive “file not found” or “access denied” errors when they click shared links that were created before the migration. The root cause is that file paths and permission contexts change during the migration, making existing links point to locations that no longer exist. This article explains why links break during mergers and provides a step-by-step admin checklist to prevent and fix broken shared links.

Why File Server Migration Breaks OneDrive Shared Links During Mergers

When a company acquires another organization, the acquired company’s file servers are typically migrated to the parent company’s tenant. This migration involves moving files from the acquired tenant’s OneDrive and SharePoint sites to the parent tenant’s infrastructure. Shared links that were created before the migration contain a unique identifier that points to the original file location — the site collection ID, list ID, and item ID in the source tenant. After migration, those identifiers no longer match any location in the parent tenant. The link becomes orphaned.

Additionally, permission inheritance changes during migration. The acquired company’s users are often moved to new Azure AD tenants, and their user principal names (UPNs) may change. Shared links that grant access to specific users by UPN or email address stop working because the recipient’s identity no longer matches the link’s access control entry. Anonymous “Anyone with the link” links also break because the underlying file GUID changes when the file is copied to the new tenant rather than moved with its metadata intact.

Another factor is the difference in sharing policies between tenants. The parent tenant may have stricter sharing restrictions, such as blocking external sharing or requiring sign-in. Links that were created under a more permissive policy in the acquired tenant may be blocked entirely after migration. Admins must audit both tenants’ sharing settings before migration and align them to prevent link failures.

Admin Checklist: Steps to Prevent and Fix Broken Shared Links

1. Audit existing shared links before migration
   Use the SharePoint Online Management Shell to run Get-SPOSite -IncludePersonalSite $true | Get-SPOSiteSharingPermissions to export all shared links from the source tenant. Save the output as a CSV file. This gives you a baseline of which files have shared links, what link types are used, and who has access. You will need this list to recreate critical links after migration.
2. Align sharing policies between tenants
   In the Microsoft 365 admin center of the parent tenant, go to Settings > Org settings > Sharing. Set the external sharing level to match or exceed the source tenant’s policy. If the source tenant allowed “Anyone” links, enable that option temporarily in the parent tenant. After migration, you can restrict the policy again. Failure to align policies will cause all “Anyone” links to be blocked.
3. Use Microsoft’s cross-tenant migration tools
   For tenant-to-tenant migrations, use the SharePoint Migration Tool (SPMT) version 3.11 or later, which supports cross-tenant migration of OneDrive and SharePoint content. In SPMT, select Cross-tenant migration > OneDrive and map source users to target users. This tool preserves file metadata and attempts to remap shared links. However, it does not guarantee that all links will work — it only remaps links that use user-specific permissions.
4. Recreate critical shared links after migration
   For links that break despite migration, use the CSV export from step 1 to identify high-priority links — such as those shared with external partners or used in business-critical workflows. Recreate these links manually by navigating to each file in the target tenant, clicking Share, and setting the same permissions and expiration dates as the original link. For bulk recreation, use the Set-SPOFile PowerShell cmdlet with the -ShareLink parameter.
5. Notify users and external partners about link changes
   Send a communication through the Microsoft 365 Message Center or a custom email template. Include the new file locations and links for critical documents. Advise users to reshare files from the target tenant rather than forwarding old links. This reduces confusion and prevents repeated access-denied errors.
6. Monitor sharing activity for 30 days post-migration
   In the Microsoft 365 admin center, go to Reports > Usage > Sharing. Review the “Shared with external users” report to see if external link usage drops after migration. A sharp decline indicates that many links are still broken. Use the Audit log to search for “AccessDenied” events related to shared links. Investigate and recreate any links that continue to fail.

If Links Still Break After the Migration

“File not found” error when clicking a shared link

This error means the link’s target file no longer exists at the expected location. The file may have been moved to a different site or library during migration. Use the SharePoint Migration Assessment Tool (SMAT) to scan the source tenant and identify where each file was moved. SMAT generates a mapping report that shows the new URL for each migrated file. Manually update the broken link with the new URL.

“Access denied” error for a link that worked before migration

This error indicates that the link exists but the user’s permissions were not migrated. This commonly happens when the user’s UPN changed during the merger. In the Microsoft 365 admin center, go to Users > Active users and verify that the affected user’s UPN matches the one stored in the link’s access control list. If the UPN changed, the user must be re-added to the file’s sharing permissions. Use Set-SPOUser -Site to bulk-update user permissions if many users are affected.

Anonymous “Anyone with the link” links stopped working

Anonymous links break because the file’s unique identifier (GUID) changes when the file is copied between tenants. There is no automated way to remap these links. The only solution is to recreate the anonymous link for each file after migration. To prevent this in future migrations, avoid using “Anyone” links for critical files. Instead, use “Specific people” links, which can be remapped by the migration tool.

Shared Link Types: Before vs After Migration Behavior

Item	Before Migration (Source Tenant)	After Migration (Target Tenant)
Anonymous (Anyone) links	Works with any user who has the link	Broken — file GUID changed, must recreate
Specific people links	Works for named users	Works if user UPN matches and file metadata is preserved by SPMT
Organization-wide links	Works for all users in the source tenant	Broken — users now belong to parent tenant, link scope does not match
Guest user links	Works for external users invited to source tenant	Broken — guest accounts must be recreated in parent tenant

Mergers and acquisitions require careful planning to avoid disrupting shared access to files. By auditing links before migration, aligning sharing policies, and using Microsoft’s cross-tenant tools, you can minimize broken links. Recreate critical links manually after migration and monitor sharing activity for 30 days. For future migrations, set the default link type to “Specific people” to ensure the best chance of link preservation.