I think that you will need to discover why the 500 Error message is occurring.   Check the server logs.   You have an error in your code somewhere.   (Please don’t post it...)

At the risk of sounding trite, first be sure that your Perl program is running properly at all.   There are many environment settings that must be “just so” in order to run a Perl CGI-script, say in Apache.   When rolling out stuff like this, I am careful not to be content with, “well, it seems to be working...”   Instead, I force myself to think, “prove to me that it is working.”   My skepticism is usually rewarded.