Flutter Web - 404 - Direct URL - No Hash: Небольшое руководство о том как справляться c page not found 404 в Flutter Web приложении.
https://www.didierboelens.com/2020/02/flutter-web---404---direct-url---no-hash/
https://www.didierboelens.com/2020/02/flutter-web---404---direct-url---no-hash/