Sign-in & Login Problems

Fix Microsoft 365 Web Apps Stuck in a Sign-In Loop

Huda Qurayshi Oct 10, 2026 870 views

Question details

Users are unable to access Microsoft 365 web applications due to a continuous sign-in loop accompanied by cookie-related errors, even though desktop apps work normally.

How to Fix Microsoft 365 Web Apps Stuck in a Sign-In Loop

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to log into Microsoft 365 web applications via a standard web browser.
Observed behavior: The web applications remain stuck in an infinite sign-in loop and display cookie-related errors. Clearing the browser data does not resolve the issue.

Before you start

Before proceeding with advanced troubleshooting, try logging into www.office.com using a Private or Incognito browser window. If this works, the issue is likely isolated to your specific browser settings or conflicting extensions.

Solution 1Recommended

Enable Third-Party Cookies in Your Browser

Web browsers often block third-party cookies by default, which can interrupt the authentication process required to sign into Microsoft 365 web apps.

Microsoft 365 relies on cross-domain authentication cookies to verify your identity across its various web services. When these are blocked, the system repeatedly prompts you to sign in.

Open Chrome Settings

In Google Chrome, click the three-dot menu icon in the top right corner and select 'Settings'.

Navigate to Cookie Settings

Click on 'Privacy and security' in the left sidebar, then select 'Third-party cookies'.

Allow Third-Party Cookies

Select the option to 'Allow third-party cookies'. Close your browser completely, reopen it, and attempt to sign into Microsoft 365 again.

Enable Third-Party Cookies in Your Browser

For Safari Users: If you are using Safari on a Mac, open Safari Preferences, click the 'Privacy' tab, and uncheck 'Prevent cross-site tracking' to allow the necessary Microsoft authentication cookies.

Solution 2

Clear Microsoft Teams Local App Data

Corrupted cached data in the local Microsoft Teams application can sometimes cause authentication conflicts that trigger a sign-in loop across the wider Microsoft 365 environment.

Solution 3

Review Permissions and Contact IT Support

If browser configurations do not fix the sign-in loop, the issue may stem from excessive or conflicting account permissions requiring administrator intervention.

Free Microsoft Office alternative

Switch to WPS Office for a Hassle-Free Desktop Experience

If Microsoft 365 web apps continue to lock you out with frustrating sign-in loops and cookie errors, consider switching to a dependable desktop solution. WPS Office is a lightweight, fully-featured alternative that allows you to work offline effortlessly without relying on complex web-based authentication.

1. Download WPS Office: Visit the official WPS website and click the free download button for your operating system.
2. Install the Software: Run the downloaded installer and follow the simple on-screen prompts to complete the setup.
3. Start Creating: Launch WPS Office to immediately open, edit, and save your existing Office files without needing continuous online authentication.

Avoid web-browser sign-in loops by using a reliable desktop applicationFully compatible with Microsoft Word, Excel, and PowerPoint file formatsLightweight installation with robust offline editing capabilitiesAll-in-one suite for documents, spreadsheets, presentations, and PDFs

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Frequently Asked Questions

Why does Microsoft 365 keep returning me to the sign-in screen?

This typically happens when your web browser is set to block third-party cookies. Microsoft 365 requires these cookies to share your authentication status across its various domain services. Without them, the system assumes you are logged out and requests your credentials again.

Will clearing my browser cache stop the Microsoft login loop?

Clearing your cache and cookies is a good first step, but it often does not resolve this specific issue. If your browser settings are still configured to block third-party cookies, or if the issue is rooted in conflicting local app data (like Microsoft Teams cache), the loop will persist even after clearing your browser data.

How can I easily check if a browser extension is causing the Microsoft 365 sign-in error?

The fastest way to test this is by opening an Incognito or Private browsing window. Since most extensions are disabled by default in private mode, successfully logging into Microsoft 365 via this method strongly indicates that an extension or strict cookie setting in your standard browser window is causing the disruption.

Login & Account Issues