Test Outlook.com in a private browsing window using a current supported browser; if that stops the flashing sign-in loop, disable the browser’s blocking extensions for Outlook.com and retry normally.
1. Isolate the browser session
- Open an InPrivate/Incognito/Private window.
- Go directly to Outlook.com and select Sign in.
- Enter the Microsoft account email address and password.
If this works, the account itself is accessible and the normal browser profile is interfering with sign-in. In the regular browser:
- Disable AdBlock, uBlock, or similar content/privacy blockers for Outlook.com.
- Close all browser windows, reopen the browser, and sign in again.
- If necessary, remove the saved cookies/site data for Microsoft and Outlook sign-in sites.
Microsoft recommends a current version of Edge, Chrome, Firefox, or supported Safari; it specifically notes that ad blockers and pop-up blockers can cause Outlook.com loading problems.^1^
2. If the private window also loops
Try another current supported browser or another device. This distinguishes a device/browser problem from an account-side sign-in problem.
Then run Microsoft’s sign-in troubleshooter. Outlook.com uses the same password as the associated Microsoft account, and Microsoft directs users who cannot sign in to this troubleshooter.^2^
If the process displays a verification request, blocked-account notice, or unusual-activity warning, complete that account-recovery flow rather than repeatedly submitting the password. Microsoft may require identity confirmation when it detects unusual activity, a new device, or travel.^2^
3. If it still flashes on every browser and device
Use Microsoft’s account sign-in assistance page: When you can't sign in to your Microsoft account. If automated recovery does not resolve it, use the can’t sign in support option linked from Microsoft’s Outlook.com support guidance.^3^
Do not post the email address, password, recovery codes, or screenshots containing personal account details in this public forum.
References
- Supported browsers for Outlook on the web and Outlook.com | Microsoft Support
- How to sign in to Hotmail | Microsoft Support
- How to sign in to Outlook.com | Microsoft Support