Im trying to use view11 to Autocad 2020 and I get error: bad argument type: numberp: nil. Does anyone have an idea how to solve this problem

You should try asking at the CadStudio site where that originated.  Since it's a .vlx file, rather than a .lsp or certain other types, we other-than-the-source people can't look into how it works in search of an answer.

Does that mean it's now unsupported since its an old progam? And developers are not active in this site? This is only the site I know that I can download view11

Please try to first load one of the newer LISP apps from the Download section here  and then load View11. We will update View11 in the meantime.
Vladimir Michl2019-09-17 22:52:11

Understood sir. View11 is helpful for beginners like me. Looking forward for the update

The update is now available on the Download page.

I have the same issue. I loaded ascpoint.lsp (2020) first and then View11 but still get bad argument error.