I don't know what my $sarah_bownds = $fb-> ... ->as_hashref is supposed to return, but if it is a hashref, I wouldn't put it into an URL like you did.
First step to verify this would be to change the last line of your code to

my $gotourl = "http://goto.this.domain/cgi/register.cgi?login=$login&i
+d=$user->{'id'}&email=$user->{'email'}&msg=201&args=$sarah_bownds";
print "going to >>>$gotourl<<<\n";
print $q->redirect($gotourl);
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