Sandcastle Help File Builder not building (or alternative)

Using SHFB i managed a few weeks ago to build myself a config for a Project. The output produced wassnt pretty, but for a library it works. Then i went on to document a ton of code. Now Today i just want to build the Html with SHFB and it doesnt work anymore... I attached a screenshot to the relevant build output.
- All Projects are .netStandard2.0
- All Projects export xml docs
- All Projects use Langversions 8.0-10.0

all this 3 facts didnt change for any of the projects i use. but yet it still doesnt work.

If this is a problem that cant be solved i am open for any alternative programm to get my existing xml docs to a Html.