When using the upload modiule and the popup opens, the same page is opened within the popup.

I have the same issue.
what is strange is it worked last night and today... "Page Not Found"
the reference is :
window.open('upload','popup'
^^^^^^

I noticed the authors referecne is :
window.open 'http://james.seng.cc/drupal/upload?#'

it seems the reference should call the function _upload_form but I'm not a PHP'er.
wish I could help more.

I installed the upload module on another site. the correct reference should be :

window.open('?q=upload'

but I can't find where it should be in the PHP code.

sorry for the spam. there are two entries in upload.module that should be :

$url = url("?q=upload");

I am closing this bug report since it has been created for a project version that is now unsupported. If the bug can be reproduced in a project version compatible with a supported Drupal release, please re-open this issue.