I have a blank install of webmin-1.950-minimal and on first start I receive this error message when I access the Running Processes module.
HTTP/1.0 500 Perl execution failed Server: MiniServ/1.950 Date: Thu, 2 Jul 2020 22:33:27 GMT Content-type: text/html; Charset=utf-8 Connection: close Error - Perl execution failed
Undefined subroutine &proc::list_processes called at /usr/local/webmin/proc/index_tree.cgi line 13.
To make workeable need to install again the proc module.
Similar problem with Scheduled Cron Jobs module, on start it not working it need to reinstall again. I tested this problems many times on two system.