Can't log in https://entra.microsoft.com/

Hello Verners Mikšus,

Greetings! Thanks for raising this question in the Q&A forum.

The error code post_request_failed is a generic MSAL.js network error. It means the browser could not complete the POST request that MSAL sends to the Microsoft identity endpoint during sign-in. Since you are signing into entra.microsoft.com, which is Microsoft's own first-party admin portal rather than a custom registered application, this is almost always caused by something intercepting or blocking that network call on your side, such as a browser extension, cached session data, a proxy, or a Conditional Access policy on the account. It is not something you would need to fix inside an app registration.

Test in a clean browser session Open entra.microsoft.com in an InPrivate or Incognito window, or try a different browser entirely (Edge, Chrome, Firefox). This rules out corrupted cache or cookies tied to a stale sign-in session.

Disable extensions and blockers temporarily Ad blockers, privacy extensions, or strict script blockers can silently drop the POST request to login.microsoftonline.com. Disable them for entra.microsoft.com and retry.

Check for a corporate proxy or firewall If you are on a managed or corporate network, confirm that the following endpoints are not being blocked or SSL-inspected:

https://login.microsoftonline.com
https://entra.microsoft.com

Try the same sign-in attempt from a different network, such as a mobile hotspot, to isolate whether the network is the cause.

Inspect the browser console for the underlying failure Press F12 to open Developer Tools, go to the Network tab, and reproduce the sign-in attempt. Look for the failed POST request around the token or authorize call and note whether it shows a CORS error, a timeout, or an HTTP status code such as 4xx or 5xx.

Pull the Correlation ID from the Entra sign-in log If you have any other way to reach the Microsoft Entra admin center, or if an admin in your tenant can check on your behalf, go to:

Microsoft Entra ID > Monitoring & health > Sign-in logs

Filter by your UPN and the approximate time of the failed attempt to capture the Correlation ID, Request ID, and failure reason. This will show whether the sign-in is actually reaching Entra and being rejected, for example by a Conditional Access policy, versus never reaching the service at all.

Rule out an account-level block If the failure happens consistently across networks, browsers, and clean profiles, ask your tenant administrator to check whether a Conditional Access policy, sign-in risk policy, or account restriction is blocking access to the Entra admin center for your account specifically.

Escalate to Microsoft Support if unresolved If the issue persists after the above steps and you can gather a Correlation ID and timestamp, open a support request through the Azure portal under Help + Support, or if you do not have a paid support plan, report it through the Entra admin center's built-in feedback option or the Azure status page at https://status.azure.com to check for any ongoing service incidents.

If this answer helps you kindly accept the answer which will help others who have similar questions.

Best Regards,

Jerald Felix.