We are having outlook authentication issues during sign in for Android and iOS Apps

Faizan Iftikhar (Mobile Telecoms Project Lead) 6

Hi Team,

Since yesterday, users in our organisation are no longer able to sign into the Outlook apps on iOS or Android. We use basic Authentication to sign into our Exchange and currently we are on-premise. I have seen a couple of posts now floating around regarding this so can a community member advise if this is a known issue and is there any solutions or a central area to get updates on this please ? Just to advise, we are having no problems using the Samsung Mail or Apple Native apps to sign into our Corporate emails.

Aleksei Kouznetcov 10 Reputation points

2024-03-27T18:10:43.3266667+00:00

Hi,

In recent days, we also cannot add accounts in Oultook on iPhone and Android. We always get the same error during authentication: Unable to login. Exchange 2019 CU14. Native Apple mail app works well.

https://testconnectivity.microsoft.com/tests/exchange all tests passes successfully. Mobile windows laptop outlook users works well.
Jayce Yang-MSFT 1,246 Reputation points Microsoft Vendor

2024-03-28T08:59:22.44+00:00

Since “we are having no problems using the Samsung Mail or Apple Native apps to sign into our Corporate emails.”，we could know that Exchange Server is working well, and this issue is related to Outlook for Android/IOS. In order to better solve your problem, it's suggested to post your issue on this dedicated forum for Outlook for Mobile for more professional help.
Thamer Lamfon 0 Reputation points

2024-03-28T20:14:09.2333333+00:00

Hi,

is there a solution ?
Safar Zoltan 5 Reputation points

2024-04-17T13:38:34.6366667+00:00

The Microsoft Outlook mobile app ignore the domain and username fields.

It's used the email address for authentication...

(Accept even if you have a non-existent email address, just match the user's UPN)
Matej B 0 Reputation points

2024-04-18T07:44:21.8466667+00:00

Yes Zoltat, that is correct i figured the same thing. For login users you e-mail, which is the cause dor authenticating error.

1 answer

Aleksei Kouznetcov 10 Reputation points

2024-03-29T06:02:40.21+00:00

The solution, as always, can be found on reddit, but not here.

Please, read: "Outlook for iOS and Android - an error occurred during authentication"

https://www.reddit.com/r/Outlook/comments/1bp044h/outlook_for_ios_and_android_an_error_occurred/

So, if you hosting local AD domain like microsoft.local or somthing like that, which is differ from your e-mail domain microsoft.com. In this case, you must retire this discrepancy.

You must ensure that Outlook users have an AD UPN that matches their email exactly.

Just Add Alternative UPN suffix in Active Directory Domain and Trust snap-in.

After that change user logon name and domain suffix in Exchange admin center.

Easter egg from M$. Happy Easter!
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1 person found this answer helpful.
Jayce Yang-MSFT 1,246 Reputation points Microsoft Vendor

2024-04-01T08:08:26.6466667+00:00

If the answer is helpful please click on ACCEPT ANSWER as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Faizan Iftikhar (Mobile Telecoms Project Lead) 6 Reputation points

2024-04-03T08:55:23.0533333+00:00

Thanks for the answer Aleksi, we did eventually stumble across this solution by fluking the sign in by removing the domain name and changing the username from the microsoft.local format to the email address (otherwise known as the UPN in Azure AD)

However, this morning our old method of sign in i.e., using the domain and Microsoft.local username is now working again ????? we are really baffled by what is going on and the lack of guidance or updates on this from Microsoft is extremely worrying.

Aleksei Kouznetcov 10 Reputation points

2024-04-04T06:04:56.36+00:00

I have rolled back the settings of some users. It is a real magic from the ms exchange team magicians.

You can find more info here: https://techcommunity.microsoft.com/t5/exchange-team-blog/released-march-2024-exchange-server-security-updates/ba-p/4075348/page/6#comments
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