Flutter - Error: Null safety features are disabled for this library

Question

I have been working on a flutter project for a long time. Now I have set up my new laptop and after reinstalling the tools for VS Code(Flutter, Android Studio) I face the error mentioned in the title of this question.

Error: Null safety features are disabled for this library.
Try removing the package language version or setting the language version to 2.10 or higher.

As advised, I have set my flutter-sdk version to >= 2.10.0 but it is still not working. To enable the NNBD I would have to enable experimental support but people advise against it until it is fully released. So what should I do to get my codebase working? Enable NNBD experimental support or is there any other solution? Here is my flutter doctor:

[√] Flutter (Channel stable, 1.22.3, on Microsoft Windows [Version 10.0.19041.572], locale en-AT)
    • Flutter version 1.22.3 at C:\flutter
    • Framework revision 8874f21e79 (6 days ago), 2020-10-29 14:14:35 -0700
    • Engine revision a1440ca392
    • Dart version 2.10.3

 
[!] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at C:\Users\xyz\AppData\Local\Android\sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
    ! Some Android licenses not accepted.  To resolve this, run: flutter doctor --android-licenses

[!] Android Studio (version 4.1.0)
    • Android Studio at C:\Program Files\Android\Android Studio
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)

[√] VS Code (version 1.50.1)
    • VS Code at C:\Users\xyz\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.16.0

[√] Connected device (1 available)
    • Android SDK built for x86 (mobile) • emulator-5554 • android-x86 • Android 8.0.0 (API 26) (emulator)

! Doctor found issues in 2 categories.

If needed, I will provide extra information/logs/files.

Answer 1

I resolved running flutter clean and flutter pub get again.