When you try to co-author a document in Word, you might see the error message “The server is not available.” This error stops you from saving changes or seeing edits from others. The problem usually happens because Word cannot reach the SharePoint or OneDrive server due to network issues, cached credentials, or a corrupted Office profile. This article explains why the error occurs and provides step-by-step fixes to restore co-authoring.
Key Takeaways: Fixing the Co-Authoring Server Error in Word
- File > Account > Update Options > Update Now: Ensures Word has the latest fixes for server communication bugs.
- Sign out of Office and sign back in: Refreshes the authentication token that connects Word to SharePoint or OneDrive.
- Clear the Office cache via Credential Manager: Removes corrupted credentials that block the server connection.
Why Word Cannot Reach the Co-Authoring Server
Word uses a live connection to a SharePoint or OneDrive server to sync changes between co-authors. When the server is unreachable, Word displays the error “The server is not available.” The root cause is almost always one of the following:
Expired or Corrupted Authentication Tokens
Office 365 uses cached tokens to authenticate with cloud services. If the token expires or becomes corrupted, Word cannot verify your identity with the server. This happens after a password change, a license renewal, or when the system clock is out of sync.
Network Interruptions or Firewall Blocks
Corporate firewalls, VPNs, or proxy servers can block the ports and endpoints that Word uses for co-authoring. Common blocked endpoints include sharepoint.com and onedrive.com.
Corrupted Office Profile or Cache
Word stores temporary files and cached data about recently opened documents. If this cache becomes corrupt, Word fails to establish a fresh connection to the server.
Steps to Fix the Co-Authoring Server Error
Follow these methods in order. Test co-authoring after each step.
Method 1: Update Office to the Latest Version
- Open Word and go to File > Account
In the Account panel, look for the Office Updates section. - Click Update Options and select Update Now
Word checks for and installs any available updates. Restart Word after the update finishes.
Method 2: Sign Out of Office and Sign Back In
- In Word, go to File > Account
Under User Information, you see your email address and a Sign Out link. - Click Sign Out
Confirm the sign-out when prompted. Close all Office apps. - Open Word again and go to File > Account
Click Sign In and enter your work or school credentials. This forces Word to request a fresh authentication token.
Method 3: Clear Cached Credentials in Windows
- Open Credential Manager
Press the Windows key, type “Credential Manager,” and press Enter. - Click Windows Credentials
Scroll down to the Generic Credentials section. - Remove all entries that start with “MicrosoftOffice” or contain “SharePoint” or “OneDrive”
Click the arrow next to each entry, click Remove, and confirm. - Restart Word and open the co-authored document
Word prompts you to sign in again. Enter your credentials and test co-authoring.
Method 4: Repair Office Installation
- Open Control Panel and go to Programs and Features
Find Microsoft 365 or Office in the list. - Right-click the Office entry and select Change
Choose Quick Repair first. If the error persists, run Online Repair. - Follow the on-screen instructions
The repair process reinstalls core Office components without affecting your documents.
Method 5: Check Network and Firewall Settings
- Disable any active VPN temporarily
VPNs can route traffic through servers that block Office 365 endpoints. - Ensure your firewall allows connections to sharepoint.com and onedrive.com
Contact your IT administrator if you cannot modify firewall rules. - Flush the DNS cache
Open Command Prompt as administrator and runipconfig /flushdns. Restart Word.
If Word Still Shows the Server Error After the Main Fix
“The server is not available” appears only on one document
The document itself may be corrupted. Open the document in a web browser (SharePoint or OneDrive) and download a fresh copy. Replace the local copy and try co-authoring again.
Co-authoring works on home network but not on corporate network
Your corporate network likely has strict firewall rules. Ask your IT team to whitelist the Office 365 IP ranges and URLs listed in the Microsoft 365 documentation.
Other co-authors see the error but you do not
The problem is on the other user’s machine. Ask them to follow the steps in this article. If the issue affects multiple users, the server or network infrastructure may be the cause.
Word Online vs Desktop: Co-Authoring Server Error Frequency
| Item | Word Desktop | Word Online |
|---|---|---|
| Error frequency | Higher due to cached credentials and local network settings | Lower because it runs entirely in the browser |
| Authentication method | Cached tokens from Office sign-in | Browser session cookie |
| Required fix complexity | Multiple steps: update, sign-out, credential removal, repair | Clear browser cache or use a private browsing window |
| Offline access | Yes, with sync pending | No |
If you frequently encounter the server error on the desktop app, consider using Word Online as a temporary workaround. Word Online does not require local credential caching and bypasses many network issues.
You can now restore co-authoring in Word by updating Office, refreshing your sign-in, clearing cached credentials, and checking your network. Start with the sign-out and sign-in method because it resolves most cases. For persistent errors, run an Online Repair of Office. As an advanced tip, use the Microsoft Support and Recovery Assistant tool to automate credential cleanup and network diagnostics.