I am debugging this ajax for quite a time now. I have this on my jQUery file:
$(\"#typeForm\").ajaxForm({
success : function(html){
alert(html);
If you cannot find a better solution for this you can encode the value to base64 encoding:
$data = array('upload_data' => $this->upload->data());
$str = base64_encode("
Nachricht empfangen!");
echo json_encode(array('file_name' => $data['upload_data']['file_name'], 'prompt' => $str));
and in the client decode it, IMO this is more safer this is also more applicable if you're processing characters from different languages.
ALSO:
to sure that no other characters will be added on the json string call exit; writer after you print it.