PHP Problem with UPLOAD_ERR_PARTIAL (File upload error code 3)

I have just spent the last 3 hours trying to figure out why only ever 3rd file would upload (and then files would only randomly upload) and i continued to get UPLOAD_ERR_PARTIAL. It turns out UPLOAD_ERR_PARTIAL can be caused by the header Connection: Keep-Alive.

If you are working on a web app that requires a lot of file uploading, make sure to use on your uploader script to set:

header("Connection: close");

This will force the connection to be closed, and for a new connection to be opened to upload the file, which allows the file to be properly uploaded.