#!/usr/bin/perl -wT

use CGI; my $q = new CGI;

#...

my ( $user_id, $name ) = identify ( $auth_token );

# ...

my $fh = $q->upload( "file" );
my $filesize = -s $fh;
die $filesize; # undef at debugging!
# ... file read routines, that resulted blank after the upgrade