Develop Reference

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

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.

I resolved running flutter clean and flutter pub get again.

Flutter release apk crash on launch

I am having an issue testing a release build on my device. If I use the app using flutter run or flutter run --release, the app runs with no errors reported and I can use the app without issue. However, using the generated APK from flutter build apk, the app crashes immediately stating the app failed to launch.
I have followed everything from here https://flutter.dev/docs/deployment/android#building-the-app-for-release so that shouldn't be the issue.
How do I begin to debug this issue?
This is the output from Flutter Doctor -v
[✓] Flutter (Channel stable, 1.20.4, on Mac OS X 10.15.7 19H2, locale en-GB)
• Flutter version 1.20.4 at /Users/student/flutter
• Framework revision fba99f6cf9 (3 weeks ago), 2020-09-14 15:32:52 -0700
• Engine revision d1bc06f032
• Dart version 2.9.2
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
• Android SDK at /Users/student/Library/Android/sdk
• Platform android-29, build-tools 29.0.3
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 12.0.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 12.0.1, Build version 12A7300
• CocoaPods version 1.9.1
[✓] Android Studio (version 4.0)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 49.0.2
• Dart plugin version 193.7547
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
[✓] VS Code (version 1.49.3)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.15.0

With release mode. You can debug what's going on with https://fbflipper.com. Just download Flipper tool, install and run it and watch the logs.
Anyway, you can consider my points about android crash:
Wrong arch: check architecture supported between apk and device
Check broken in native libraries or class not found: Some libraries broken reference in release with ProGuard
Manifest broken: Some thing kind of missing or incorrect in configuration of manifest file

Running/Debugging Flutter app very slow after upgrading to latest SDK version 1.20.4

I'm facing this problem after upgrading to latest stable version 1.20.4
Earlier I was using Flutter 1.12.13+hotfix.5 and debug/run speed was good enough.
Is anyone else also facing this issue? Or could anyone help by suggesting some solutions or reasons as to why this is happening?
I am using a Windows 10 machine.
Running flutter doctor -v yields the following output
• Flutter version 1.20.4 at D:\flutter
• Framework revision fba99f6cf9 (8 days ago), 2020-09-14 15:32:52 -0700
• Engine revision d1bc06f032
• Dart version 2.9.2
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
• Android SDK at C:\Users\amani\AppData\Local\Android\Sdk
• Platform android-29, build-tools 29.0.2
• ANDROID_HOME = C:\Users\amani\AppData\Local\Android\Sdk
• Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
• All Android licenses accepted.
[√] Android Studio (version 3.5)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin version 42.1.1
• Dart plugin version 191.8593
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
[√] VS Code (version 1.49.1)
• VS Code at C:\Users\amani\AppData\Local\Programs\Microsoft VS Code
• Flutter extension version 3.14.1
[√] Connected device (1 available)
• Android SDK built for x86 (mobile) • emulator-5554 • android-x86 • Android 10 (API 29) (emulator)
• No issues found!```

i had a simular issue , for me i return to the previous stable version and everything goes good ,
run flutter downgrade to return to the previous fluter version install on your machine

Solved the issue by deleting Flutter SDK and then replacing it with newly downloaded SDK.
It seems that upgrade caused some files to get corrupted in the SDK directory.

flutter embedding - Upgrading Pre 1.12 Android Projects Breaks Plugins

While building my flutter project, I was forced to follow the instructions in this link https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects for my shared_preferences package to work.
I followed the instructions there. Now my plugins seem to not work. for example signing with google throws this error: error MissingPluginException(No implementation found for method init on channel plugins.flutter.io/google_sign_in)
Similar errors happen with almost all of my plugins.
here is my flutter doctor -v logs
• Flutter version 1.10.15-pre.404 at C:\src\flutter
• Framework revision 9093cf15f6 (2 hours ago), 2019-11-04 22:30:16 -0500
• Engine revision 7b968ff95f
• Dart version 2.7.0
[!] Android toolchain - develop for Android devices (Android SDK version 29.0.1)
• Android SDK at C:\Users\Ajmal Jalal\AppData\Local\Android\sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.1
• Java binary at: C:\Program Files\Android\Android Studio1\jre\bin\java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
X Android license status unknown.
Try re-installing or updating your Android SDK Manager.
See https://developer.android.com/studio/#downloads or visit https://flutter.dev/setup/#android-setup for detailed instructions.
[√] Android Studio (version 3.5)
• Android Studio at C:\Program Files\Android\Android Studio1
• Flutter plugin version 41.0.2
• Dart plugin version 191.8593
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
[√] VS Code (version 1.39.2)
• VS Code at C:\Users\Ajmal Jalal\AppData\Local\Programs\Microsoft VS Code
• Flutter extension version 3.5.1
[√] Connected device (1 available)
• Android SDK built for x86 • emulator-5554 • android-x86 • Android 9 (API 28) (emulator)
! Doctor found issues in 1 category. ```

This question was answered here in flutter's github page, and the answer there resolved my issue:
https://github.com/flutter/flutter/issues/44161

I can't install my own Application from the play store

I used flutter to make a small app, I publish it on the play store. Problem is, I can't install on any avd I have. I get the "your device is not compatible with this version" (or a similar message depending on the android version I tried with).
I just followed the instructions on how to make an apk and an app bundle (they both didn't work). How can I make it downloadable and usable in an play store enabled avd ?
Here is a flutter doctor -v
[✓] Flutter (Channel stable, v1.5.4-hotfix.2, on Mac OS X 10.14.5 18F132, locale
fr-FR)
• Flutter version 1.5.4-hotfix.2 at /Users/moo/development/flutter
• Framework revision 7a4c33425d (6 weeks ago), 2019-04-29 11:05:24 -0700
• Engine revision 52c7a1e849
• Dart version 2.3.0 (build 2.3.0-dev.0.5 a1668566e5)
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
• Android SDK at /Users/moo/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling
support)
• Platform android-28, build-tools 28.0.3
• Java binary at: /Applications/Android
Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build
1.8.0_152-release-1343-b01)
• All Android licenses accepted.
[✓] iOS toolchain - develop for iOS devices (Xcode 10.2.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.2.1, Build version 10E1001
• ios-deploy 1.9.4
• CocoaPods version 1.7.1
[✓] Android Studio (version 3.4)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 36.0.1
• Dart plugin version 183.6270
• Java version OpenJDK Runtime Environment (build
1.8.0_152-release-1343-b01)
[✓] VS Code (version 1.35.0)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.1.0
[✓] Connected device (1 available)
• Android SDK built for x86 • emulator-5554 • android-x86 • Android 7.0 (API
24) (emulator)

You can't install an apk from the store written in flutter on the emulator because the ABI of the emulator is x86, and the apk in release mode(the mode that is on the store) can't be installed on devices with x86 ABI.
You can't even run the application in release mode on the emulator