File server to SharePoint migration before Server 2016 ends

What changes on January 12, 2027?

Microsoft’s Windows IT Pro blog (updated October 22, 2026) says Server 2016 then stops getting security updates, bug fixes and technical support.

Microsoft plans paid Extended Security Updates for up to three years, covering critical and important security updates only. Pricing and availability are still to be announced.

Before you plan, list what else the server does:

• Shared folders, usually mapped as a drive letter like S: or P:.
• The accounting file for QuickBooks Desktop or Sage 50.
• Sign-ins, if people log in to their PCs with an office account.
• Printers, scans to folder and backups that point at the server.

What goes to SharePoint, and what stays on a server?

What’s on the server	Where it goes	Why
Shared folders (Word, Excel, PDFs, drawings)	A SharePoint document library per team or area	Everyone with access can open, sync and share it
Each person’s home folder	Their own OneDrive	Microsoft counts OneDrive separately from the SharePoint storage pool
QuickBooks Desktop company file	A Windows computer running Database Server Manager, or a move to QuickBooks Online	Intuit says: “You must install and run this tool on the server computer”
Sage 50 company data	A shared folder on a Windows computer acting as the server	Sage says: “Company data files must be stored in a shared folder on the server”
Old closed years nobody opens	An archive library, set to read-only	Keeps the working libraries small enough to sync

If you run QuickBooks Desktop 2023, read what to do now that QuickBooks Desktop 2023 is discontinued first. On Sage 50, check what the Sage 50 to QuickBooks Online conversion leaves out before you pick a home for the file. If the move includes hundreds of AutoCAD drawings, see how to update their title blocks in one batch.

What breaks when files move to SharePoint?

• Long paths. SharePoint caps the full decoded path, including the file name, at 400 characters.
• Office’s 260-character limit. Microsoft’s path length page says Office desktop apps on Windows can’t open files whose full path exceeds 260 characters. Synced files sit under C:\Users\name\Company Name\, so paths that fit on S: can pass it.
• Blocked characters. OneDrive and SharePoint reject " * : < > ? / \ | in file and folder names.
• Blocked names. Microsoft’s restrictions page lists .lock, CON, PRN, AUX, NUL, COM0 to COM9, LPT0 to LPT9, vti, desktop.ini and any name starting with ~$.
• Permissions. Microsoft’s migration permissions page says Read becomes Read, Write becomes Contribute and Full control stays Full control. Special permissions such as Deny “aren’t saved,” and users not matched in Microsoft 365 get the library’s default permissions.
• Excel links. Workbooks that pull from another file on S: keep pointing at S: until you change the source.
• Too much to sync. Microsoft recommends no more than 300,000 files per synced library, and the same slowdowns can hit at 300,000 items across all synced libraries, shortcut folders included.
• Storage. Business plans get 1 TB plus 10 GB per license. A tenant that stays over its limit risks going read-only.

Example: an office with 15 Microsoft 365 licenses has 1 TB plus 150 GB of SharePoint storage. A 900 GB shared drive fits. A 1.4 TB drive needs a cleanup or extra storage first.

The free SharePoint path too long checker flags long paths and blocked names in a folder list from your server.

How do you move it with Migration Manager?

1. Clean the folder list. Run it through the path checker, shorten deep folders, rename blocked names and delete what nobody needs.

2. Plan the libraries. One library per top-level folder or team, with permissions set on the library, not on single files. Microsoft supports up to 50,000 unique permissions per library and recommends staying under 5,000.

3. Install the agent. On a computer that can reach the share, sign in with a Windows account that has Read access to every share you’re moving. Then:

1. In the SharePoint admin center, select Migration center.
2. Under “For file shares”, select Get started.
3. Select the Agents tab, then Add.
4. Select Download agent setup file and open it.
5. Choose User Credential Authentication, enter a SharePoint admin’s username and password, and select Next.
6. Enter the Windows account’s password and select Install.

The agent’s working folder needs at least 150 GB free. The Migration Manager overview says the server holding the files must support SMB 2.0 or higher.

4. Scan first. In Migration Manager’s settings, turn Only perform scanning on and run a task for each share. Fix what the scan reports, then turn it off.

5. Set the copy options. Turn on Preserve file share permissions if your office sign-ins are synced to Microsoft 365. Microsoft recommends setting Migration auto rerun to Off.

6. Copy one team first. Create a task with the share’s network path as the source and the SharePoint library as the destination. Let that team work from SharePoint for a week.

7. Cut over on a weekend. Set the old share to read-only, then run the last tasks with Migrate files modified after set to the date of the first copy. Remove the mapped drive from every PC.

8. Connect each PC. Microsoft’s sync page recommends OneDrive shortcuts over the Sync button, because shortcuts work on all devices while sync is tied to one.

How do you check it worked?

1. Compare counts. Compare file counts and size in the Migration Manager task reports with the server folder’s Properties.
2. Open the deepest files. On a synced PC, open ten files from the longest paths in your folder list.
3. Check access as staff. Have one person from each team confirm they see their folders and nothing else.
4. Fix Excel links. In each linked workbook, go to Data > Queries and Connections > Workbook Links, select More Commands (...) next to the old file, then Change source.
5. Test the accounting file. Open it in multi-user mode from two workstations on its new host.
6. Keep the old share read-only for a full week, then back it up and shut the server down before January 12, 2027.

What are your options?

Option	Good for	Watch for
Do it yourself with Migration Manager	One server, a few hundred GB, simple folder access	Paths, names and permissions must be fixed before the copy
Third-party migration tool	Large shares or complex permissions	What it does with permissions; someone still plans the libraries
Your IT provider	Moving the server, sign-ins and accounting file together	Who signs off on the library plan and the cutover date
Bring in an outside team (Cleanups & bulk changes)	Cleaning thousands of paths and names before the copy	Needs read access to the share and time with whoever knows the folders

FAQ

Can I keep running Windows Server 2016 after January 12, 2027? It keeps running, but without security updates, bug fixes or support. Paid Extended Security Updates cover critical and important security updates only.

Can the QuickBooks Desktop file go in SharePoint? Not for shared use. Database Server Manager must run on the computer that hosts the company file, so it needs a Windows computer on your network or a move to QuickBooks Online.

Do home folders count against SharePoint storage? No. Microsoft’s pool of 1 TB plus 10 GB per license doesn’t include each user’s OneDrive.

Will my folder permissions copy across? Read, Write and Full control copy across when your users exist in Microsoft 365. Deny doesn’t, so check sensitive folders by hand.