MS Teams on iPhone not opening and sends error messages

Question

MS Teams on iPhone not opening and sends error messages

Davidm 0

I have been trying to open MS Teasm on my iPhone using my work/school account (& I am also the administrator). I am unable to open the app, because it directs me to Authenticator and then sends me an error message as below

We're unable to complete your request

unauthorized_client: The client does not exist or is not enabled for consumers. If you are the application developer, configure a new application through the App Registrations in the Azure Portal at https://go.microsoft.com/fwlink/?linkid=2083908.

I am not an application developer, so am unsure that this means.

Any suggestions on how to fix this?

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2 answers

Your answer

Answer 1

Dear @Davidm

This error occurs when Microsoft Authenticator tries to sign you in using a personal Microsoft account (consumer identity, such as Hotmail, Outlook.com, or an unlinked personal alias) instead of your organizational Work/School account (Microsoft Entra ID).

Because your Microsoft Teams app is set up to authenticate against an organizational tenant, the system rejects personal consumer credentials with ⁠unauthorized_client⁠.

Step 1: Fully Sign Out and Clear Cached Accounts on iPhone

Open the Microsoft Authenticator app on your iPhone.
Check if your Work/School email is listed. If a personal Microsoft account is listed under the same email, tap it and select Remove Account.
Open iOS Settings > Teams > toggle on Clear app data (or uninstall and reinstall the Teams app from the App Store).

Step 2: Authenticate Directly Using Work Credentials

Open Microsoft Authenticator > tap + (Add Account) > select Work or school account. Sign in using your official work/school email address and password.
Once the account profile is active in Authenticator, open Microsoft Teams.
When prompted to sign in, ensure you explicitly select or type your Work or School account (do not select "Personal" if prompted between two account types).

Step 3: Verify Admin/Domain Identity (As the Administrator)

If the prompt persists, your work email might be tied to an unmanaged personal Microsoft account created under the same address:

Go to Microsoft 365 Admin Center > Microsoft Entra ID Portal on a desktop web browser.
Sign in with your admin credentials.
Navigate to Users > All users and verify that your UPN (User Principal Name) matches the exact work email address you are entering on your phone.
If you have a personal account registered under the same email, go to Microsoft Account Management to add a distinct primary alias for your personal account so it stops conflicting with your organization's directory

Please refer to this document: Manage custom domain names in your Microsoft Entra ID

Please let me know if you have any further questions.

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Answer 2

Davidm 0

I was unable to identify if the Authenticator app with my email was related to Teams or something else. I deleted it and now I am unable to add the account. I get these two messages (see attached)

I also went into the Microsoft Account Management and got not find any tab indicating users or reference to multiple users. All I have is one subscription for Microsoft 365 Personal. Is it that I do not have a work / school account? Seems odd, as I am also the Administrator!

I created a "Personal" account on Teams and Authenticator and that seemed to work. Oddly it has the same information as the Teams account I used on desktop version???

All a bit confusing!!!

[Moderator note: Personally Identifiable Information removed]

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Screenshot 2026-08-18 at 16.43.00

BabybooHN 3,040 Reputation points Independent Advisor

2026-08-19T01:15:33.31+00:00
Dear @Davidm

Thank you for clarifying. Being the sole Administrator on the account changes things significantly—it explains why you got locked out after deleting the entry in Authenticator.

Here is what is happening and how to regain access:

Why this is happening

Broken MFA Loop:

When you deleted the account from your Authenticator app, the server-side setting requiring Multi-Factor Authentication (MFA) stayed active. The system is still pushing sign-in prompts (like the 77 in your screenshot) to a device that no longer has the matching keys stored locally, leading to the Code: -42104 / Tag: 4vlpo error.

Personal vs. Work/School Account Conflict:

If your admin email was used to create both a Personal Microsoft Account (for your M365 Personal subscription) and a Work/School (Entra ID) Account, Microsoft treats them as two separate identity systems under the hood even if they share the same email address.

When you created/signed into Teams Personal, it authenticated fine because it bypassed the tenant's admin MFA policy.

However, your Admin portal (admin.microsoft.com) and Teams Business access live under the Work/School identity, which is currently blocked by the deleted MFA configuration.

How to regain Admin access

Option A: Use a Secondary Admin or Emergency "Break-Glass" Account

If you have another account in your organization with Global Admin rights:

Log in to the Microsoft 365 Admin Center > Microsoft Entra Admin Center using that secondary admin account.

Go to Users > All Users and select your primary admin account.

Click Authentication methods in the left menu.

Click Require re-register MFA (or manually delete the old Authenticator method and select Add authentication method).

On your next sign-in with your main account, you will be prompted to set up the Authenticator app again from scratch.

Please refer to this document: Manage user authentication methods for Microsoft Entra multifactor authentication

Option B: Sign In Using an Alternate Verification Method

If you previously registered a mobile phone number or backup email for your admin account:

Open an InPrivate / Incognito browser window and go to https://admin.microsoft.com.

Enter your admin email and password.

When the Authenticator prompt appears, click "I can't use my Microsoft Authenticator app right now" or "Other ways to sign in".

Choose Text/SMS or Phone Call to receive a verification code.

Once inside, go to https://aka.ms/mfasetup to re-bind your Authenticator app.

Option C: Contact the Data Protection Team (If you are the ONLY Admin)

If you are the sole Global Admin and have no alternative sign-in methods configured, you will not be able to reset MFA yourself for security reasons. You will need to contact Microsoft Commercial Support to reach the Data Protection Team:

Call the phone support line for your region: Microsoft Admin Support Phone Numbers.

Inform the automated system/agent: "I am the sole Global Administrator, I am locked out due to MFA, and I need a ticket raised with the Data Protection Team to reset my MFA registration."

If calling phone support hasn’t been effective and you’re getting disconnected, there is another option you can consider as a workaround to reach the right team. You can sign up for a new Microsoft 365 tenant by creating a trial subscription here: Microsoft 365 Business Plans and Pricing | Microsoft 365

Once that new tenant is created, you’ll be able to access the Microsoft 365 admin center and submit a support ticket directly from there. In the ticket, explain that you’re requesting assistance from the Data Protection Team for your original tenant, due to being locked out as the only admin with MFA issues. This method often helps bypass the automated loops because you’re able to submit the request from an authenticated admin center, even if it’s under a temporary tenant.

Note: Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.

Hope this helps clear up why the Personal account worked while the Admin account threw errors. Let me know how it goes.