Did you also change your code to look like the following: 
my $error = join('', <$PROG_STDERR>);
my $err = $!;
die "Error reading data from STDERR: $err"
    if !eof($PROG_STDERR);

[download]

If you didn't, you haven't shown than an error even occurred.

Before I do anything else, I'm going to worry about making sure an error actually occurred and about getting the right error message when one does occur.

In reply to Re^3: open3 and illegal seeks by ikegami
in thread open3 and illegal seeks by brainsick

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