We have got an extjs 3.1.1 form with file upload field (http://www.extjs.com/deploy/dev/examples/form/file-upload.html from here, the latest). After successful submission the reply is {"success":true} with application/json content type. We use Zend Framework as backend, json is generated with json helper.
This works like a charm in firefox but in explorer offers downloading a file. The saved file contains the successful json reply. If we remove the file upload field, everything works. But this way (naturally) the form is not multitype. Beside this we have bunch of other forms (without multipart) that works with the same json reply method.
The only way that we managed to do upload submission with explorer was to remove the content type and to respond with plain text that contained a valid json.
Is thery any way to handle multipart form json reply properly with explorer?