The following are some of the mostly frequently asked questions related to mod_perl configuration issues (and the answers, of course).

My CGI/Perl code is returned as plain text instead of being executed by the web server.
Check your configuration files and make sure that +ExecCGI is turned on in your configurations. + adds an option without resetting any options that were previously set. So this is how the <Location>section might look:

<Location /perl>
    SetHandler perl-script
    PerlHandler Apache::Registry
    Options +ExecCGI
    PerlSendHeader On
</Location>
My script works under mod_cgi, but when called via mod_perl, I get a Save As prompt.
You probably sent the HTTP header via print( ):

print "Content-type: text/html\n\n";

If this is the case, you must make sure that you have:

PerlSendHeader On

in the configuration part of the <Location> section:

<Location /perl>
    ...
    PerlSendHeader On
</Location>

This adds a little overhead to the output generation, because when this configuration is enabled, mod_perl will parse the output and try to find where the header information ends so it can be converted into a proper HTTP header. It is meant only for mod_cgi emulation with regard to HTTP headers.

Is there a way to provide a different startup.pl file for each individual virtual host?
No. Any virtual host will be able to see the routines from a startup.pl file loaded for any other virtual host.