flutter - 版本解析失败

Question

突然在项目中，我得到了一个错误“import js.dart”或类似的内容。我发现了一个命令提示“flutter channel beta”，所以我进行了更改，升级，然后一切都没有了。
当我在flutter中运行任何命令时，出现错误:

Building flutter tool...
The current Dart SDK version is 2.10.0-0.0.dev.flutter-a3815b6590.

Because flutter_tools depends on collection >=1.15.0-nnbd <1.15.0-nullsafety.2 which
  requires SDK version >=2.9.0-18.0 <=2.9.10, version solving failed.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

先感谢您

Answer 1

我只是cd到flutter根文件夹，然后“git pull origin –ff-only”，最后键入“flutter upgrade”。