This fix has worked flawlessly for me. It is being used on a high traffic contest site where the public can upload photos as a guest, and we have no problems with it at all.

This plugin is probably the most useful WP plugin I have ever used. Which is why I am hoping the developers get it fixed so that html5 uploading works as the default.

I was able to get uploading to work in all browsers including IE9 and IE10 by doing the following.

1. Open /js/upload.js
2. On line 24 change the runtimes order to flash,html5,html4
3. On line 37 change flash_swf_url to ‘/wp-includes/js/plupload/plupload.flash.swf’

This doesn’t seem the perfect solution because all the browsers that were working (chrome, firefox, etc) default to flash now instead of html5. But at least it’s working in all browsers for me now.

If we could find the reason that making the runtimes order html5,flash,html4 hangs in IE everything would be perfect.