A Microsoft desktop and app virtualization service that runs on Azure. Previously known as Windows Virtual Desktop.
Azy Alam check how the session hosts were joined, if the VMs are Azure AD joined or domain joined, you must use the correct type of account. A local admin account will not work on a domain joined VM and vice versa. Also make sure you are using the correct username format such as ******@domain.com for Azure AD or DOMAIN\username for domain joined machines, because using the wrong format often looks like a wrong password. Check that the user is assigned to the application group in Azure Virtual Desktop and that the session host shows as Available and Healthy in the host pool. It is also worth confirming that the account is not locked and that the password has not expired.
rgds,
Alex