Hello, @Solomon Tran,
Welcome to the Microsoft Q&A platform!
Based on your description, I understand that you receive the error “Ex0D6BFD. Microsoft.Exchange.Data.DataValidationException|There are multiple primary SMTP addresses. Please ensure there is only one primary address for each address type.” when you update the recipient type and email address of your mailbox at the same time.
If it is convenient for you, could you please provide a screenshot of the error you got, and we might be able to glean more information from it.
From the error code you have provided, this error usually occurs when a mailbox is assigned more than one primary SMTP address, which is not allowed. You can use the following command in PowerShell to check your SMTP address information (Primary SMTP address starts with SMTP:).
If you really do not have multiple primary SMTP addresses set up, regarding your reference to “update these 2 fields at the same time”, what operations exactly did you make? Your reply will help to solve your problem as soon as possible, so I hope you can get back to me in your free time.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Thank you for your support and understanding.
Best Wishes,
Alex Zhang