When you try to Migrate a mailbox from Exchange On Premise to Exchange we faced the below error
to be able to get more information about this issue , open the power shell and run the below command
Test-MigrationServerAvailability -ExchangeRemoteMove -Remoteserver “Server URL”
And got the below error
We found that something is not working perfectly with the certificate published to the internet , we fix the certificate and re run the same command again but with credentials for accessing the servers URL
As you see it works fine now , after fixing the Certificate publishing issue