[Flutter/dart] ServicesBinding.defaultBinaryMessenger was accessed before the binding was initialize

Overview

Suddenly the above error message appears and the app crashes. As in the error message and the article on the net, adding

WidgetsFlutterBinding.ensureInitialized();

at the top of main() doesn't solve the problem.

Cause and solution

It seems that the cause was accessing assets from another isolate. (reference)

As a solution, I used flutter_isolate and the above error disappeared.

Click here for how to use flutter_isolate

Lastly

(Added on 2021/2/20)

Since flutter_isolate creates a new dart execution environment in another isolate, it will not be recognized as "another isolate" and no error will occur (reference). However, flutter_isolate officially supports only some libraries such as notification, so it is at your own risk.