Hello @Guang Li
As suggested by Andreas, you would need a registration key to complete this task of adding an existing VM to a host pool, you can follow these steps:
Uninstall Existing Agents:
- RDP into the VM you want to add to the host pool.
- Uninstall the following agents: Remote Desktop Agent Bootloader Remote Desktop Service Infrastructure Agent
Generate a Registration Key:
- Sign in to the Azure portal.
- Navigate to Azure Virtual Desktop and select Host pools.
- Select the host pool you want to add the VM to.
- Go to Registration key and generate a new key.
Install Azure Virtual Desktop Agents:
- On the VM, install the Azure Virtual Desktop Agent and Azure Virtual Desktop Agent Bootloader.
- During the installation, use the registration key you generated.
Verify the VM in the Host Pool:
- After the installation, the VM should appear in the host pool.
This process ensures that the VM is properly registered with the host pool using the correct agents and registration key
If you encounter any issues, feel free to ask for further assistance!
References: https://learn.microsoft.com/en-us/azure/virtual-desktop/add-session-hosts-host-pool?tabs=portal%2Cgui&pivots=host-pool-standard#register-session-hosts-to-a-host-pool
https://learn.microsoft.com/en-us/azure/virtual-desktop/agent-overview?source=recommendations
Add existing Azure VM to session host pool (Azure WVD)
Add session hosts to a host pool - Azure Virtual Desktop
If I have answered your question, please accept this as answer as a token of appreciation and don't forget to thumbs up for "Was it helpful"!