In this scenario we had some Issues with VM replication on Azure. So customer had removed the Protection completely and he was trying to configure it again. In this process he had also uninstalled the ASR Provider as well from the Hyper-V server and even the ASR Agent was also uninstalled it seems.
So we installed the Provider first on the Hyper-V host and then we were trying to install the MARS Agent, but that was just failing to even launch the Wizard.
After researching a bit on this issue, we found out that this type of issue can occur if the following registry key exists on the Hyper-V Host while installing the MARS Agent:
We searched for the above Registry key and it was present on the Server. SO we went ahead and Renamed the key 9E3CC81A48FC05646B4407520C8CC01D To 9E3CC81A48FC05646B4407520C8CC01D_OLD and then we tried to re-install the MARS Agent again on the Hyper-V server. This time we were able to launch the Agent installation Wizard successfully and we could configure it fine as well.
So, this was one more case where it proved that how the Stale Registry entries can cause issues with the new installations or set ups.
Support Escalation Engineer
Microsoft Security and Manageability Division