Lost ALL access when adding new domain

Question

Hi, 

I have Exchange Online with a couple of domains already added as email addresses. This has been running fine until today. 

I just tried to add a third domain, and it prompted me to login to Go Daddy to change the DNS entries for it. 

Half way through setup, the admin inteerface suddenly said I do not have sufficient privileges and I couldn't browse to any other part of the admin portal. 

I closed the browser and tried signing in again, and now none of my email/password combinations work. 

I've tried signing in with admin accounts, normal user accoutns but all say this:

"

We don't recognize this user ID or password"

What has happened to my Exchange online and how can I sort it??

Answer 1

Hi Neo,

Thanks. I have now created a second admin user that is using the onmicrosoft.com domain. But I still don't have an answer as to why this happened.

The effect was immediate. As  soon as I added the domain, the users' login domain was changed. So this is not an issue with ADSync (which in my case runs every 3 hours).

Answer 2

Hi UserMC,

If the Office 365 user account (ends with onmicrosoft.com) and the on-premises user (ends with contoso.com) has the same UPN prefix, then DirSync could link these two users and update the Office 365 user’s UPN to the contoso.com suffix.

Therefore, to ensure the existing Office 365 global admin won’t be affected by the DirSync tool, it recommended that you create a default onmicrosoft.com account with the UPN prefix which doesn’t exist in the on-premises, and skip the “updating users” step after you add the domain in Office 365.

Also, if you encounter any issues in the future when using Office 365, please feel free to post/open a new thread with details in our forum, and we will be glad to be of an assistant.

Answer 3

Hi Felix,

I did skip step 2. I forgot to mention that the users that had their domain changed were only those Synced from my on premise Active Directory using AAD Sync. These users did not even appear in the list shown in step two.

I have a few users that were created "In Cloud" and they were not updated with the tenant domain.

So for some reason, all users that are synced from my on-premise AD were updated to use the tenant domain onmicrosoft.com.  I have now created a second In Cloud only admin login just in case this happens again.

But I have the .co.uk version of the domain to add still.

Answer 4

hi usermc,

the issue may be caused by updating users in the step 2. in this scenario, please click the skip the step at the bottom of the page or don't select any users.


for further investigation, could you provide your tenant domain and the custom domain you tried to add? to protect your privacy, i have sent you a private message to collect the information. you may access the private message here.

https://community.office365.com/user/conversations

thanks,

felix

Answer 5

Turns out what it had done is change EVERY user's email address to the default domain (ending in .onmicrosoft.com). This meant that NO users could login, and even myself as admin could not login.  

I manged to find out online that you add "onmicrosoft.com" to the end of the email and managed to login. But then I had to manually change every users login details for them to be able to get access again from Outlook .

Why did this happen? And is it going to happen again? I need to add the same domain but the .co.uk version.