The new Sametime 8.5.1 Meeting Server and Media Manager still refuses to install or upgrade. So I decided to re-install the recently unregistered and uninstalled Media Manager 8.5.

I started to create a new deployment plan because the previous plan was intended for version 8.5.1. There is now a dropdown where you can select the version for which you want to create the deployment plan.

So far, so good. I must have looked damm ned stupid when I wanted to connect to the commuity server within the deployment plan.
Nothing is offered to me at this stage. Somehow logically, I have already updated the Community Server to version 8.5.1.
Therefore I cancelled at this point and tried to install the media server 8.5 using a 8.5.1 deployment plan.

The connection to SSC was successful and the list of deployment plans was loaded. It was … empty.

So, that was it. Fazit after several hours frustration:

You cannot install or upgrade Sametime 8.5.1 Media Manager because because it fails to update the status in SSC after almost one hour of installation, and you cannot install 8.5 Media Manager when you already have updated the Community Server to 8.5.1 because you can not create an appropriate community plan. The same applies to the Meeting Server.

Any advice, what to do?