Errno 9] Bad file descriptor

[joblack]

Thanks for the answers so far. It's not my code I'm just curious how
that could happen:

Starting point:
...
        self.status['text'] = 'Processing ...'
        try:
            cli_main(argv)
        except Exception, e:
            self.status['text'] = 'Error: ' + str(e)
            return
...
cli_main:

    keypath, inpath, outpath = argv[1:]
...
    with open(inpath, 'rb') as inf:
        serializer = PDFSerializer(inf, keypath)
        with open(outpath, 'wb') as outf:
            filenr = outf.fileno()
            serializer.dump(outf)
    return 0

PDFSerializer.dump:

    def dump(self, outf):
        self.outf = outf
...