First of all let me tell you that I've already searched for some answers, and while it helped me out a bit, my main problems remain unresolved.
I used the file uploader (Version 9.8.0) @ http://blueimp.github.io/jQuery-File-Upload/
(1st problem)
Everything seems to work fine until I start uploading. After it finishes uploading, it says the following error for each image (instead of the "upload successful" message).
On Google Chrome it says: "SyntaxError: Unexpected token <"
on Mozilla FireF. it says: "SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data"
I searched some solutions but I can't figure out how to apply these solutions. And btw, it adds the image, despite the error.
The method you are calling is throwing an error page with html (starting with < and cannot be parsed in JSON), if you look at the network tab in your browser.
For example in Google Chrome:
I had a similar problem on ASP.Net MVC with a different uploader, when one of the parameters was sent as null and it wasn't nullable on the controller.