I occasionally get upload failures on Internet Explorer

We occasionally see upload failures. These errors so far have seemed to only happen on Internet Explorer, but I can't confirm that yet (still trying to get browser details as these errors happen). How are we best to debug this problem?

This is indeed due to old version of IE. We can't upload files larger than 100Mb as IE9 lacks support of File API (we cover that briefly in our docs and there is a handy reference table).