Sorry BrowserUK! Only just saw this post. I don't think that is the problem

while <$upload_filehandle>
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is supposed to read the input. It is initialised with

my $upload_filehandle = $query->upload("myfilename");
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On the otherhand,

UPLOADFILE
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is supposed to be the output of the script: a copy of the uploaded file on the hard disk. I agree that the naming of my filehandles could have been much better