Does the applet return this error when you try to upload ?
Did you check that simple upload from browser work ?
http://www.yourserver.com/process.jsp

If you could share a testing URL then I could check what's wrong.

Yes, HTTP can upload files over 2GB. It allows to split files in chunks, upload each chunk and recompose the original file on server-side from chunk. We have a customer uploading 8GB DVD with this solution. Resume is supported (depending on server-side script). But resume will apply on each chunk on...

Ok, you're using JFileUpload applet (that will be loaded in the browser) and JSPUpload script (that will be loaded on server-side) to handle upload request. Your installation seems correct. Let's check it together: 1- JFileUpload. You said you've installed it under document root so you should have: ...

For HTTP upload, you should have both renamed filename and original filename in the upload request. For instance, if I upload d:/addons.jpg then server-side script receive: selectedfullfilename=D:\addons.jpg todo=upload uploadfile=test_rename.jpg ... For FTP upload, we cannot pass it and I don't see...

The problem comes from 'template' parameter. The applet tries to find info on the renamed file. Try to add the following extra parameter, it should fix this issue:
<PARAM NAME="param8" VALUE="selectedfullfilename">
<PARAM NAME="value8" VALUE="true">

Since 2.1, fill in bucket name and leave all others parameters empty.

How to upload to a S3 bucket with public read/write permissions ?

Since version 2.1 we have a solution to avoid exposing AWS secret key. It is based on the new S3 HTML POST feature. It's now possible to generate a policy parameter an sign it. The policy document includes rules for upload (bucket name, acl ...). You sign this document with your AWS id + secret key....

Great !

It should be under scripts/ or / but not under applets/jfileupload/lib/. Also, you have to make sure you can access the file directly from browser through: http://www.yourserver.com/scripts/i18n.properties If you get and 404 or 403 error then it means the file is not installed or your server is not ...