Device unregistered when signing into outlookSolved

Participant
Discussion
2 months ago Dec 23, 2025

Hey everyone, 

I’m stuck with a Conditional access issue and I’m hoping someone here has seen this before. 

We have a supervised iOS device enrolled in hexnode, and we’ve also configured the Hexnode Email policy. The device shows as enrolled and compliant in hexnode without any issues. 

But when the user tries to sign in to outlook using Microsoft entra credentials, it fails with: “Device unregistered” 

What I’m noticing: 

  • The user is signing in through Edge browser 
  • The login flow shows the 2FA/MFA prompt 
  • After the user finishes authentication, it fails and throws the “device unregistered” error 
  • If we disable Mfa in the policy, outlook login works fine 

So, it looks like Conditional access is blocking it, but I don’t get why it says “unregistered” when the device is already compliant in Hexnode. 

Anyone know what causes this or what I should check next? 

Replies (1)

Marked SolutionPending Review
Participant
2 months ago Dec 25, 2025
Marked SolutionPending Review

Hey! Yep, I’ve hit this exact same “device unregistered” error before. 

Device was enrolled, supervised, compliant… everything looked fine on Hexnode’s side, but Outlook refused to sign in once conditional access + mfa kicked in. 

For me, the issue was simple: 

The iphone was not actually registered in Microsoft entra ID. 

Once I registered it, Outlook login started working normally again. 

What fixed it for me. 

Just do the Entra registration directly from the Hexnode app: 

  1. Open the Hexnode app on your iPhone 
  2. You should see an option called “Register with Entra ID” 
  3. Tap it → hit continue 
  4. It’ll redirect to Microsoft authenticator 
  5. Sign in using the Entra credentials 
  6. Tap Register 
  7. Once it confirms registration, just finish the flow 

After that, I stopped getting the “device unregistered” error. 

This Hexnode doc explains the same steps too: 

https://www.hexnode.com/mobile-device-management/help/microsoft-entra-id-device-registration/ 

Hope that helps. 

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