Permission & Access Issues

Fix Authentication Cookie Errors When Accessing Guest SharePoint Sites

Camila Milosovich Oct 10, 2026 869 views

Question details

A guest user is blocked from accessing a shared SharePoint site or OneDrive folder due to an authentication cookie error.

Fix Authentication Cookie Errors When Accessing Guest SharePoint Sites

Product: SharePoint and OneDrive
Device & OS: not provided
Scenario: Attempting to access a customer's shared SharePoint site after being prompted to enter a new guest access code.
Observed behavior: The system displays an 'authentication cookie could not be updated' error message, preventing the user from viewing the shared files.

Before you start

Ensure you have the exact sharing link provided by the host and have access to the email inbox where the guest access code was sent.

Solution 1Recommended

Clear Browser Cache and Cookies

Removing outdated or corrupted browser cookies forces SharePoint to generate a fresh authentication session.

Authentication cookie errors typically happen when your browser holds onto expired session data that conflicts with a newly required Microsoft access code. Clearing your browser's cache and cookies is the most effective way to resolve this.

Open browser settings

Click the three-dot menu in the top right corner of your browser (such as Google Chrome or Microsoft Edge) and select 'Settings'.

Navigate to privacy settings

Find the 'Privacy and security' section in the left sidebar and click on 'Clear browsing data'.

Select cookies and cache

Check the boxes for 'Cookies and other site data' and 'Cached images and files'. Select 'All time' as the time range.

Clear data and restart

Click the 'Clear data' button. Once finished, completely close and restart your browser, then try signing into the SharePoint site again.

Fresh Session: After clearing cookies, you will be prompted to enter your email and request a new guest access code. This new code should now process successfully.

Solution 2

Use an Alternative Browser or Incognito Mode

Using a private browsing window or a different browser bypasses existing extensions and session conflicts.

Solution 3

Contact the Microsoft 365 Administrator

If local browser fixes fail, the host organization's administrator may need to reset your guest permissions.

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Frequently Asked Questions

Why do I keep getting authentication cookie errors on SharePoint?

This error usually occurs when corrupted or outdated browser session data clashes with Microsoft's access token system, especially after an old guest access code expires and a new one is requested.

Does Incognito or Private browsing help bypass cookie errors?

Yes. Opening the SharePoint link in an Incognito or Private window prevents the browser from using your existing cookies, which often resolves the 'cookie could not be updated' loop immediately.

What should the Microsoft 365 admin check if the error persists?

The administrator should review the guest user's profile in Microsoft Entra ID (formerly Azure AD), revoke any existing active sessions, and reissue a new guest invitation link.

Document & File Issues