Can't sign in outlook Server Error: 401:undefined|undefined:undefined

Me too, i have same problem with you like 2 hours ago.

Same here, I'm guessing it denotes a server error, but it has been about 4, 5 hours.

I tried using outlook.com on google chrome (regular + incognito) on a PC, MS Edge (regular + Incognito) on PC, google chrome on 2 samsung phones, Internet app on 1 samsung phone (regular + Private Browsing).

This is the error i'm getting.

UTC Date: 2025-07-10T03:52:51.512Z
Client Id: 96E6C9C177784058BAC20E3C049F43B0
Session Id: 4d21ac8e-52ee-4250-b468-01ffdc76dba4
Client Version: 20250620014.20
BootResult: fail
Back Filled Errors: Unhandled Rejection: Error: 401:undefined|undefined:undefined
err: Error: 401
esrc: StartupData
et: ServerError
estack: Error: 401
    at Object.w [as createStatusErrorMessage] (https://res.public.onecdn.static.microsoft/owamail/hashed-v1/scripts/owa.mailindex.ad3a7e4e.js:1:1039)
    at https://res.public.onecdn.static.microsoft/owamail/hashed-v1/scripts/owa.mailindex.ad3a7e4e.js:1:161561
st: 401
efe: SYBPR01CA0153

I can login from account.live.com, but even from there when I try to open the email page(outlook), it gives error 500.

clientIPAddress 219.89.9.125
X-ClientId: 96E6C9C177784058BAC20E3C049F43B0
request-id 98a59907-b0df-b8d2-7335-b7718a8d2f3d
X-Auth-Error System.Runtime.InteropServices.COMException
X-OWA-Version 15.20.8901.24
X-FEServer DB9PR01CA0006
X-BEServer DB8P195MB0597
Date:7/10/2025 3:56:42 AM

Go try to open outlook.com at new Incognito window and sign in. maybe will work it.

I’m having the issue too. Is it everyone having the same problem?

Same issue with mine. Please help