Uploading an Image hangs indefinitely

We recently completed a site in Sitefinity 8.0.5710 and upon moving the application into the production environment we noticed that we are having issues uploading a new image in the admin.  Upon selecting an image from the local system and clicking the "Upload and Publish" button, the progress for the image progresses to 100% uploaded and turns green, but the spinner continues to show on the screen and the page does not redirect back to the Library page.  Upon looking at the JavaScript console, an error is displayed saying "Uncaught TypeError: Cannot read property 'UploadResult' of undefined". It appears it is looking at the result of the POST to Telerik.Sitefinity.Html5UploadHandler.ashx and when looking at the response from that handler the response just contains an empty JSON array.  Upon closing out the page and returning to the Library that the image was uploaded to, the record was created successfully however the thumbnail of the image is just a broken image.  Has anyone had similar issues with this page and how were you able to resolve this issue?

Just ran into this today myself. Does no-one have a response for this?

Still don't have a solution, but we have determined the issue to be specific to the server setup.  We've tried numerous installations of Sitefinity (incuding the quantum demo site) which have worked on other environments, but fail on the specific server that the error had occurred previously.   Because I mentioned this to Tech support, they pretty much closed the case and told us we were on our own as they see it as a non-standard server setup.

Looks like in my case it was an issue with a rewrite rule we had in place. We have a rule to enforce lowercasing and the Html5UploadHandler's POST request was getting rewritten to a lowercased version, which also means it turns into a GET, which explains why the response is empty.