SUMMARY
Details on how to leverage Microsoft Fix It for removing Windows Agent when it will not uninstall properly.
ISSUE
The Windows agent cannot be uninstalled from the Add/Remove Programs List.
RESOLUTION
Please keep in mind that the below process on installing the Unitrends agent via the MSI on a Hyper-V Host whether clustered or not can cause an unexpected reboot. Please perform these operations when migrations are possible or when a small amount of downtime is acceptable.
For uninstalling/reinstalling Hyper-V CBT Driver please review:
How to uninstall and re-install CBT on Hyper-V
Uninstall via installation media
Locate the prior release MSI from agent archive and you can put the old MSI back on the box and run an uninstall operation using it, This will often clean up the older release, if you can identify which specific version it was.
Microsoft fixit tool
Microsoft has a tool called Microsoft Fix It that you can use to help remove the agent. Just download the program and run it, choosing the Uninstall option. After this is finished, install the current agent from the appliance's samba share, then kick off a quick backup to verify that it works.
Note: The Fix It tool is valid for Windows server OSes, it is not limited to workstations.
Microsoft (fixit) Meta Removal Tool
Microsoft Legacy Meta Removal Tool
Reference: https://support.microsoft.com/en-us/topic/fix-problems-that-block-programs-from-being-installed-or-removed-cca7d1b6-65a9-3d98-426b-e9f927e1eb4d
Find and remove UUID from registry allowing re-install of agent directly
In admin cmd prompt, run "msiexec.exe /i <path to installer> /l* <path to log file>" and then read the generated log. You will likely find references to a key that uses a UUID that may not be directly associated with our product. In some cases MSI installation will create the product ID, but will not add the name, making registry search to remove our agent difficult or impossible. from the errors reported in the MSI log, remove those specific keys (we suggest making a key backup first just in case) and then retry. several attempts may be necessary as the installer may abort at a later registry object.
CAUSE
This can be due to registry corruption or other issues, such as an old agent that was installed to a different path, someone deleting the PCBP or moving it prior to the new install, or because the old install failed to properly uninstall. This leaves widows with registry keys that point to uninstall files that do not exist.
NOTES
For more information, see https://support.microsoft.com/en-us/mats/program_install_and_uninstall