错误：指定的语言版本太高。支持的最高语言版本为 2.13

Question

出于某种原因，我将 Flutter 从 2.5.2 降级到 2.2.3。

现在：Flutter version 2.2.3 和 Dart version 2.13.4

在 pubspec.yaml 中：

environment:
  sdk: ">=2.12.0 <3.0.0"

当我运行项目时，它可以工作，但我从控制台收到此消息：

Failed to precompile devtools:devtools:
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/shelf_proxy-1.0.1/lib/shelf_proxy.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/http.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/client.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/exception.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/request.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/response.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/streamed_request.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/base_client.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/base_request.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
^
/C:/Users/user/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/http-0.13.4/lib/src/base_response.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.13.
// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
^

Here 就是它所说的：“flutter clean，然后运行项目。”它不能解决问题。

我该如何解决这个问题？

Answer 1

解决方案 1：

删除pubspec.lock文件。

然后运行，

flutter clean

和

flutter pub get

解决方案 2：

flutter pub cache repair

免责声明：运行上述命令时，互联网连接速度非常快，否则会浪费数小时的生产时间。 （这将重新下载安装在您电脑上的每个包，我的意思是每个包的每个版本）