access denied error for file upload

We have a file upload form and a client uploaded two files.  The first we can access just fine but the second one gives us a window with an 'access denied' error.

Any idea?

This error occurs when the upload of a file is not completed properly or the process was interrupted by unstable connections or early form submissions by the user before the entire upload process was finished..

Kindly ask the client to re-upload the second file, if the issue persists please notify us.

Sorry or any inconveniences caused.