We use the API to upload images for our content management system. A lot of times the CDN version of the image will get accessed before it exists and the "no such key" error gets cached, so I have to manually go in and purge that file from the cache.
I can't see any good reason for the CDN to cache a "no such key" error. Please either do not cache them or give the option to not do so.
Thanks very much!