Wanting to know how to solve failed to disable the mailbox due to a conflict in directory settings in office 365 mailbox? You’re in the right place.

I noticed the same error on a user account and was not sure of appropriate steps to get rid of the error and followed some steps as per Google but in vain. Fortunately, I fixed it using the the following steps.
Before we begin, check the recipient type of the affected mailbox in Exchange Online powershell.

Great, the recipient type is user mailbox. It’s a time to export the mailbox content as pst file and disable the mailbox in on-premise using the (disable-mailbox test248) command.

Wait until the changes replicate to O365. Once they are done, enable the on-premise object but the recipient type should be a remote user mailbox.
Enable-remotemailbox “test248” -RemoteRoutingAddress test123@techieberry.onmicrosoft.com

Wait for the sync again and assign the Exchange Online license to the user account and check the status.

The failed to disable the mailbox due to a conflict in directory settings message is disappeared now. Finally, import the pst to the user mailbox.
Now It’s Your Turn:
Did I Miss Anything? Or maybe you have a question about something that I covered.
Either way, I’d like to hear from you. So go ahead and leave a comment below.
Worked perfectly, appreciate it
I’m glad I could help 🙂