failed to add RHV to veeam inventory v12

Need more details - what exact build of Veeam v12? Have you thought about updating to v13?  What version of RHV?  Did you check the logs?

I would suggest contacting support for this one.  Please also note that the community is not technical support.

​@rania  - just wanted to follow up to see if you got an answer to your inquiry?  If so, please mark the best answer that helped the most, even if your own.  Look forward to assisting further if needed.