Much of ABCUpload works via the ABCUpload Progress Module. This is a .NET HTTP Module designed to intercept page requests. It manages the data that's been received to ensure optimal use of memory and automatically fixes corrupt uploads.
ASP.NET is designed to handle uploads conforming to RFC 1867. Client browsers are supposed to submit multipart forms in this format but unfortunately many contain bugs which result in corrupt uploads being submitted. ABCUpload has been established many years and during this time we've adapted our code to handle every kind of corrupt upload we've ever come across.
Rather than present invalid data to ASP.NET ABCUpload pre-vets uploads and when it finds corruption it automatically fixes it before passing the data through to ASP.NET.