Commented Unassigned: ajaxfileupload - fails on server side [27671]

I have a project that uses several ajaxfileuploads throughout many pages. Everything was working fine in production and development. One day it all just stopped. I have traced the problem to ys.Extended.UI.AjaxFileUpload.ProcessorHtml5.upload.

I realize this might be a permissions issue so I have given every user on my development server full access to the temp directories. By everyone I mean every account and group on the server, including "everyone". I have given them permissions to my temp directory (%USER%) and the windows temp directory.

I have watched and when I click the upload button on the control it creates a directory called _AjaxFileUpload in the windows\temp directory and then fails. I never get the onUploadComplete event to fire on the server.

I have updated the libraries through NuGet just to be safe.

I have created a new project with nothing but an ajaxfileupload control and have the same problem.

I really need some help figuring this out. Please provide any feedback. I will provide any information, files, source, etc. you need to help.
Comments: I'm going to ask a basic question: Are you using the ToolkitScriptManager? Can you specify the errors you are getting?