Please file tickets when you encounter these. A lot of the "great errors in rustc" are by their nature reactive: we need to see what people try when they hit corners that haven't gotten as much love. async/await uses multiple somewhat advanced features under the covers that have a tendency to provide either verbose or confusing errors. We're slowly improving them, but having good examples of real world cases is incredibly useful to speed up that process. This is what allows us to have extra information with recommendations.