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Fix Microsoft 365 Sign-In Loop and App Login Issues
Question details
The user is unable to sign in to Microsoft 365 desktop applications and online services due to a persistent sign-in loop and JavaScript error prompts.
- Product
- Microsoft 365
- Device & OS
- Windows
- Scenario
- Attempting to access and authenticate Microsoft 365 apps or web services on a desktop computer.
- Observed behavior
- The sign-in process loops repeatedly or displays an error stating JavaScript is required, even after clearing browser data, enabling JavaScript, and reinstalling Office.
Verify that your Microsoft account credentials are correct by successfully signing in on a completely different device, such as your smartphone, to isolate the issue to your current PC.
Create a New Windows User Profile
A corrupted Windows user profile is a common cause of persistent Microsoft 365 sign-in loops that reinstalling Office cannot fix.
Sometimes the local Windows account data handling the authentication tokens becomes corrupted. Creating a fresh administrator account forces Windows to generate new, clean registry entries for the Microsoft sign-in interface.
Click the Start menu, type 'cmd', right-click on 'Command Prompt', and select 'Run as administrator'.
Create a new user account with administrative privileges using Windows Settings (Accounts > Family & other users > Add someone else to this PC) or via command line prompts.
Log out of your current Windows session entirely, and then log in using the newly created Windows user profile.
Open Word or Excel in the new profile and attempt to sign in. If successful, your original Windows profile is corrupted and you will need to migrate your files to this new profile.
Update Software and Run the Recovery Assistant
Outdated software configurations can trigger fake JavaScript errors during the Microsoft 365 login process.
Try WPS Office for a Hassle-Free Experience
If Microsoft 365 sign-in loops are preventing you from working, WPS Office is a highly compatible, lightweight, and free alternative that lets you edit your documents immediately without complex account authentication issues.
- 1. Download the Installer: Visit the official WPS Office website and download the free installation package.
- 2. Install the Software: Run the downloaded file and follow the simple on-screen instructions to set up the software on your PC.
- 3. Edit Your Files: Open WPS Office and double-click your existing Microsoft documents to resume your work instantly without any sign-in loops.
Frequently Asked Questions
Why does Microsoft 365 say my browser doesn't support JavaScript during login?
This is often a false error caused by a corrupted browser cache, overly strict privacy settings blocking Microsoft's login scripts, or a corrupted Windows user profile interfering with the authentication pop-up window.
What should I do if creating a new Windows profile doesn't fix the sign-in loop?
If a new administrator profile does not resolve the issue, contact your Microsoft 365 IT administrator with your device details and exact error codes, or use the Microsoft Support and Recovery Assistant (SaRA) tool to perform a deep diagnostic scan.
Can I use my Microsoft 365 documents if I am stuck in a sign-in loop?
Microsoft 365 desktop apps restrict editing capabilities if you cannot verify your subscription via sign-in. However, you can open and edit your local .docx, .xlsx, and .pptx files using a free alternative like WPS Office while you troubleshoot the Microsoft issue.
