"_method"=>"put", "action"=>"update", "spec"=>{"photo"=>"Blue-Wild- Flower-1-1024x768.jpg"}, "id"=>"10", "controller"=>"spec"}
If you can see the file name and not something like : "photo"=>#<ActionController::UploadedStringIO:0xb70611f4>
There's a mistake. Maybe you forgot the multipart on the form?