Sign-in & Login Problems

How to Fix OneNote Sync and Unsupported Server Response Sign-In Errors

Natalie Taylor Oct 12, 2026 868 views

Question details

The user is unable to synchronize notebooks in OneNote due to an unsupported server response during sign-in, despite using valid credentials.

How to Fix OneNote Sync and Unsupported Server Response Sign-In Errors

Product: Microsoft OneNote
Device & OS: Windows
Scenario: Attempting to sign in to the OneNote desktop application to sync and access personal or work notebooks.
Observed behavior: OneNote stops synchronizing data and displays an unsupported server response error message when signing in, even though the same login credentials work perfectly in other Microsoft services.

Before you start

Ensure your Windows operating system is fully updated and temporarily disable any third-party VPNs or strict firewalls, as these network tools can sometimes block or intercept Microsoft server authentication requests.

Solution 1Recommended

Clear Office Credentials in Windows

Removing corrupted or outdated login data from Windows Credential Manager forces OneNote to prompt for a fresh, clean authentication token.

Open Credential Manager

Press the Windows key on your keyboard, type 'Control Panel', and press Enter. Navigate to 'User Accounts', then click on 'Credential Manager'.

Locate Generic Credentials

Click on the 'Windows Credentials' tab and scroll down until you see the 'Generic Credentials' section.

Remove Office Entries

Look for any saved credentials that contain 'MicrosoftOffice' in the name. Click the dropdown arrow next to each relevant entry and select 'Remove'.

Restart and Sign In

Close the Control Panel, launch the OneNote desktop application, and follow the prompt to sign in with your Microsoft account credentials again.

Verify Synchronization: Once you have successfully signed back in, right-click on your notebook name and select 'Sync This Notebook Now' to confirm the connection is restored.

Solution 2

Force Open via OneNote for the Web

Launching the notebook directly from the web browser can sometimes bypass local application cache issues and instantly restore the sync connection.

Solution 3

Adjust Authentication Settings via Registry Editor

For advanced users, modifying the Active Directory Authentication Library (ADAL) registry key can resolve deep-rooted sign-in blocks on Windows systems.

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Frequently Asked Questions

Why does OneNote say 'unsupported server response'?

This error generally happens when the authentication token saved locally on your Windows device becomes corrupted or outdated. It prevents the application from securely handshaking with Microsoft's sync servers.

Will I lose my unsynced notes if I clear Windows credentials?

Clearing credentials only deletes the saved login token, not the local cache of your notes. However, any notes made offline will remain pending locally until a successful sync occurs after you sign back in.

What should I do if the registry fix and credential reset fail?

If those solutions do not work, the issue may lie within a damaged Windows user profile. Try creating a brand-new Windows user account through your system settings and see if OneNote signs in correctly on that fresh profile.

Login & Account Issues