hello,
i can’t read/write Json file when i build my game to an Android Device, tried a lot of solutions posted in unity Answers but with no hope 
here’s an example of what i want to read from the file in the android game:
When posting scripts, it’s better to use code tags Using code tags properly - Unity Engine - Unity Discussions
And post as much relevant code as possible. Your image doesn’t show you are starting a coroutine(I’m going to assume you are).
I think your filepath value might be wrong. I would say check www.error to see if it’s giving you an error back to make sure it’s actually finding the file. If it is, I’d check to make sure your json is in a valid format and the class you are casting it into is valid.
I have not used jsonMapper, so I don’t know what it is looking for. I use json.net or unity’s json utility.