The Problem:

Input in console: dart pub add platform:^3.1.3

Output:

Running pub upgrade…
Resolving dependencies… (1.6s)
Because flutter_tools depends on platform 3.1.4 which doesn’t match any versions, version solving failed.

You can try the following suggestion to make the pubspec resolve:

• Consider downgrading your constraint on platform: dart pub add platform:^3.1.3
  Error (1): Unable to ‘pub upgrade’ flutter tool. Retrying in five seconds… (8 tries left)

I’ve upgraded flutter and installed test package, and then this error keeps showing up no matter what i try to do.