When everything goes well, I can retrieve the body from response.body() with no problem. 
Althought, when a validation error occurs on server (in my case, duplicated email) it sends the error to frontend and when I try to access the error body response.errorBody() the following info is retrieved: 
"E/API Activity: onResponse: PostSalao okhttp3.ResponseBody$1@84d856e"
I expected to get something like "error: email already used".
As you may see on this video on (10:08), he does the same thing I'm doing on my code, but he retrieves the erros correctly (10:17).
What am I doing wrong?
fun postCliente(cliente: Cliente) {
        val TAG = "API Activity"
        val apiInterface: ApiInterface
        apiInterface = ClientApi.getClient().create(ApiInterface::class.java)
        val clientePostCall = apiInterface.postCliente(cliente)
        mProgressBar.visibility = View.VISIBLE
        clientePostCall.enqueue(object: Callback<Cliente> {
            override fun onResponse(call: Call<Cliente>, response: Response<Cliente>) {
                mProgressBar.visibility = View.GONE
                if(response.isSuccessful){
                    try {
                    Toast.makeText(context,"Usuario " + response.body()!!.name + " criado com sucesso.",Toast.LENGTH_SHORT).show()
                        val backHomeIntent = Intent(context, MainActivity::class.java)
                        context.startActivity(backHomeIntent)
                    } catch (e: NullPointerException) {
                        Toast.makeText(context, "Problem is unknown: ", Toast.LENGTH_SHORT).show()
                    }
                }else {
                    try {
                        val errorBody = response.errorBody().toString()
                        Toast.makeText(context, "Dados incorretos", Toast.LENGTH_SHORT).show()
                            Log.e(TAG, "onResponse: " + errorBody )
                    } catch (e: IOException){
                        Toast.makeText(context, "Problem is unknown: ", Toast.LENGTH_SHORT).show()
                    }
                }
            }
            override fun onFailure(call: Call<Cliente>, t: Throwable) {
                mProgressBar.visibility = View.GONE
                Log.e(TAG, "onFailure: " + t.localizedMessage)
            }
        })
    }