Microsoft 365 Error Codes

How to Fix HTTP 404 Error When Signing In to Microsoft 365 Applications

Emma Brown Sep 25, 2026 869 views

Question details

The user encounters an HTTP 404 (Not Found) error when trying to authenticate and sign in to a Microsoft application.

How to Fix HTTP 404 Error When Signing In to Microsoft 365 Applications

Product: Microsoft 365 Applications
Device & OS: not provided
Scenario: Attempting to access and authenticate into a Microsoft application or service.
Observed behavior: Instead of completing the sign-in process, the application displays an HTTP 404 error, indicating that the requested sign-in page or service endpoint cannot be found despite standard troubleshooting.

Before you start

Before altering system settings, check the official Microsoft Service Health status page to ensure there are no ongoing server outages affecting authentication endpoints.

Solution 1Recommended

Isolate the Issue by Testing Alternative Networks and Devices

Determine whether the HTTP 404 error is caused by a local network restriction, a specific device configuration, or an account-level glitch.

Switch to a different network

Disconnect from your current Wi-Fi or Ethernet connection and connect to a different network, such as a mobile hotspot, to bypass potential firewall or ISP restrictions.

Test on a different device

Attempt to sign into the Microsoft application using a completely different computer or mobile device connected to the same network.

Test with an alternative account

If you have a secondary Microsoft account, try signing in with it to determine if the 404 error is strictly tied to your primary user profile.

Isolate the Issue by Testing Alternative Networks and Devices

Solution 2

Verify Windows Internet Options and TLS Security Settings

Ensure your computer's internet security protocols are correctly configured to establish a secure connection with Microsoft's sign-in servers.

Solution 3

Change Your Computer's DNS Settings

Switching to a reliable public DNS server can resolve routing issues where your computer fails to locate the correct Microsoft sign-in endpoint.

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Use WPS Office as a Seamless, Free Alternative

If persistent Microsoft 365 sign-in errors and server disruptions are preventing you from accessing your work, consider switching to WPS Office. It provides a robust desktop experience that doesn't require complex cloud authentication just to edit your local files.

1. Download the software: Visit the official WPS Office website and click the free download button to get the installer.
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Frequently Asked Questions

Why does an HTTP 404 error occur specifically during Microsoft sign-in?

An HTTP 404 error means that the requested webpage or server endpoint could not be found. During a Microsoft sign-in, this usually happens because the application's authentication link is outdated, there is a DNS resolution failure, or Microsoft's backend authentication service is temporarily unavailable.

Should I enable older SSL/TLS versions in Internet Options to fix this error?

No. You should only ensure modern protocols like TLS 1.2 and TLS 1.3 are enabled. Enabling obsolete protocols like SSL 3.0 or TLS 1.0 poses significant security risks and will generally not resolve modern Microsoft 365 authentication errors.

What should I do if the 404 error persists across multiple devices and networks?

If you have tested different networks, devices, and user accounts but still receive the same HTTP 404 error, the issue is almost certainly on the application or service provider's end. You will need to wait for the application developers or Microsoft to investigate and restore the broken sign-in endpoint.

Microsoft Office Error Codes