Microsoft 365 Error Codes

How to Fix Microsoft 365 HTTP 404 Error for login.microsoftonline.com

Aamir Naveed Akram Sep 25, 2026 868 views

Question details

Users encounter an HTTP 404 error when attempting to authenticate and sign in to Microsoft 365.

Fix Microsoft 365 HTTP 404 Errors for Login.microsoftonline.com

Product: Microsoft 365 / Azure Virtual Desktop
Device & OS: Windows 11
Scenario: Signing in to Microsoft 365 or Azure Virtual Desktop, particularly during morning sign-in routines.
Observed behavior: The authentication page fails to load, throwing an HTTP 404 error for login.microsoftonline.com due to restrictive Internet Explorer proxy policies or LAN settings.

Before you start

Ensure you have administrative privileges on your Windows machine, as modifying Internet Options, LAN settings, or Group Policies requires admin access.

Solution 1Recommended

Enable Automatically Detect Settings in Internet Options

Adjusting the local LAN settings in Windows often resolves proxy conflicts that cause the HTTP 404 login error.

Windows 11 and older operating systems may still rely on legacy Internet Explorer network configurations for authentication traffic. Clearing hardcoded proxy paths allows the system to reach Microsoft's login servers smoothly.

Open Control Panel

Press the Windows key, type 'Control Panel' into the search bar, and press Enter to launch the application.

Navigate to Internet Options

Click on 'Network and Internet', then select 'Internet Options' to open the Internet Properties dialog box.

Access LAN Settings

Switch to the 'Connections' tab at the top of the window and click on the 'LAN settings' button located near the bottom.

Configure Automatic Detection

Check the box next to 'Automatically detect settings'. Ensure that the 'Use a proxy server for your LAN' box is unchecked unless specifically required by your organization's network.

Apply and Test

Click 'OK' to save the changes, close the Control Panel, and attempt to sign in to Microsoft 365 again.

Enable Automatically Detect Settings in Internet Options

Confirmed Fix: This method has successfully resolved the login.microsoftonline.com 404 error on Windows 11 23H2 environments.

Solution 2

Update Group Policy Settings for Internet Explorer

If LAN settings revert automatically upon restarting, a Group Policy Object (GPO) might be overriding them. Removing or modifying these legacy policies resolves the root cause.

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Frequently Asked Questions

Why do I get an HTTP 404 error on login.microsoftonline.com?

This error typically occurs when network proxy policies or legacy Internet Explorer settings misdirect your authentication traffic. It is especially common in Azure Virtual Desktop environments during initial morning sign-ins when outdated policies are applied.

Will changing my LAN settings affect other internet connections?

Enabling 'Automatically detect settings' usually improves general connectivity by allowing Windows to find the best network configuration dynamically. However, if your company strictly mandates a manual proxy, consult your IT administrator before changing it.

What should I do if the 404 login error returns after I reboot my PC?

If the error returns after a system reboot, it means a Group Policy Object (GPO) is pushing the restrictive Internet Explorer settings back to your machine upon login. Your IT department must update or delete the conflicting GPO targeting the Internet Explorer registry keys.

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