exit status 1 expected '}' before ':' token

Projects Programming
3

You seem to be trying to include quotation marks inside a String

If that really is what you want to do then you need to "esacpe" the quote marks in the String like this

String json = { "deviceDefault@2017idp2group9\": \"deviceDefault@FAVORIOT\", \"data\": {\"light\":\"ON\"}" }  ;

void setup()
{
  Serial.begin(115200);
  Serial.println(json);
}

void loop()
{
}

But is that what you want/need to do I wonder ?