IIS File upload fails for large files returns 404

This could be because the request filtering in more than the allowed size limit.

Check the iis log files to get a request code. It would be something like,

Status Code Substatus sc-win32status(windows system error code) time-taken
404 13 0 1120

links below has more info on the substatus message:



if 404.13 is the status then increase the allowed content size then go to Request Filtering option in the IIS under the particular site and select Rules->Edit Feature Settings on the right hand pane and increase the value for Max allowed content length.