Unable to delete Shared Mailboxes

[jblanzaderas]

We are trying to remove a shared mailbox to convert them into Groups, however we are getting this error message. 

Error:

An Azure Active Directory call was made to keep object in sync between Azure Active Directory and Exchange Online. However, it failed. Detailed error message: Another object with the same value for property proxyAddresses already exists. RequestId : xxxxx The issue may be transient and please retry a couple of minutes later. If issue persists, please see exception members for more information.

Can anyone help us why are we getting such error and how to successfully delete the shared mailbox. thank you so much

[#2]

The error message suggests that you have a duplicate attribute conflict. It's a bit weird to see this when trying to delete an object, but it is what it is. Try removing the corresponding user object from the admin center or via Remove-MsolUser.

[#3]

I filed a support ticket to this and the team is still looking into it. There isn't any duplicate value in place - however, when we ran a script in PowerShell the dualwrite value was set to True/enabled: Not sure what does that means tho. 

[#4]

Did you try removing it via the Remove-MsolUser cmdlet?

[#5]

yes this is because of recent update from MS that they have enabled dual write feature for all tenants and this will be permanent feature as of now.
https://techcommunity.microsoft.com/t5/exchange-team-blog/exchange-online-improvements-to-accelerate...

I faced various issues like not able to add alias.

Getting error: Another object with the same value for property EmailAddresses already exists.
The issue may be transient and please retry a couple of minutes later. If issue persists, please see exception members for more information.
Cmdlet-UnableToWriteToAadException]

If you look at the error details it says "UnableToWriteToAadException". When we connect to powershell of the tenant and run command:
- Ran command: Get-OrganizationConfig | fl IsDualWriteEnabled
IsDualWriteEnabled : True

A support ticket and you need to tell MS to disable the feature. Then you can remove shared mailbox.