in reply to URI::Escape::escape_char error when posting to a form inside perl script
Welcome to the monastery.
According to the HTTP::Request::Common documentation, the request() method, when used with POST, takes its list of key-value pairs as an arrayref:
$ua = LWP::UserAgent->new;
$ua->request(POST 'http://somewhere/foo', [foo => bar, bar => foo]);
You're using a hashref (\%Fields). I'd suggest changing your request() call to:
my $Page = $Browser->request(POST $URLtoPostTo, [%Fields]);