Illegal choice detected with Unlimited Image field I have an image field in a content type that uses the image widget. Whenever I select an image to upload, it gives the error: "An illegal choice has been detected. Please contact the site administrator."

The image thumbnail appears as normal, however, there is no way to submit the form (returns errors) and you can't add more images.

I haven't made any changes to the form (just some CSS stuff for presentation).

How can I fix this?
I had similar issue, fixed it by changing one of my required field from radio buttons to "select list".