Hopefully this helps someone else as it had me head scratching for a little while..
When creating the Host Pool, make sure that you haven't made the fatal error of using the Azure Active Directory Credential INSTEAD of the Local AD Domain Credential.
i.e do not use USER@m365xxxxx.onmicrosoft.com to domain join, even if it links back to the domain - this is where the conflict arrises.
Instead, use your full internal domain UPN.
USER@prefix.domain.co.uk
Re-deploy your same configuration and you should find it goes through now without any problems.
Additional findings....
Albeit my mistake above was an easy one, it does appear the error is directly linked to the domain join process.
If you go into your resource groups, locate the session host and MSTSC directly to it. Try the domain join process yourself, you'll probably find the credentials you're using are wrong, or the account doesn't have the right privileges.
Additional findings....
Albeit my mistake above was an easy one, it does appear the error is directly linked to the domain join process.
If you go into your resource groups, locate the session host and MSTSC directly to it. Try the domain join process yourself, you'll probably find the credentials you're using are wrong, or the account doesn't have the right privileges.