Consult the server's error logs and you'll see that you're getting a prototype mismatch error because two things are trying to declare the subroutine head with different prototypes.

If you bother to read the documentation for LWP::Simple it explains just why you're getting that error and what the workaround is.

Note that if you are using both LWP::Simple and the very popular CGI.pm module, you may be importing a head function from each module, producing a warning like "Prototype mismatch: sub main::head ($) vs none". Get around this problem by just not importing LWP::Simple's head function, like so:

        use LWP::Simple qw(!head);
        use CGI qw(:standard);  # then only CGI.pm defines a head()
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Then if you do need LWP::Simple's head function, you can just call it as LWP::Simple::head($url).