Mailbox migration/endpoint issue

Question

I am trying to migrate 2 accounts from on premises Exchange to EOL, these are the last on premises accounts and need to move before I upgrade our Exchange environment.

All other accounts were already in EOL when I started here so this is the first time I have had to migrate a mailbox in this environment.

The on premises Exchange setup is currently a single hybrid server running Exchange 2013 CU23, we also use AADC for directory sync between the domain and Azure.

When I try to set up the migration I get the error "The connection to the server 'mail.domain.com' could not be completed." when I get to the Confirm migration endpoint screen.

I have checked the credentials stored for the migration endpoint and even tried to set up a new connection using a domain admin account that has Exchange admin privileges explicitly set. When I try to set up the new endpoint it cannot detect the server settings, if I manually enter the FQDN of the server it gives the same error as when I try to set up the migration.

Running through the hybrid setup wizard does not give any errors, it sees and confirms everything and seems to be happy with it all.

What could be causing this and how do I fix it?

Answer 1

@Gareth Davies
Before creating migration endpoint, you need to make sure MRS proxy is enabled on your Exchange server:

Get-WebServicesVirtualDirectory | fl server,MRSProxyEnabled,ExternalUrl  

If the MRS proxy is enabled, you can try to disable it and enable again.

Then make sure the EWS external URL could access from external your organization successfully:

In the first step, for the "email address", you need to enter a mailbox which AD account is synced to AAD, this email address will be used to verify the migration endpoint:

If above settings correct, the FQDN of Exchange server will be filled automatically without need to typing:

Otherwise, you can get an error like picture below: