Flutter plugin not installed error; When running 'flutter doctor'

Safe fix for Mac (Android Studio 4.1+). It is in a different directory now, but the symbolic link helps.

Just run this command in the Terminal:

ln -s ~/Library/Application\ Support/Google/AndroidStudio4.1/plugins ~/Library/Application\ Support/AndroidStudio4.1

If you have a different Android Studio version or an installation folder, adjust the command accordingly.

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel beta, v0.9.4, on Linux, locale en_IN)
[✓] Android toolchain - develop for Android devices (Android SDK 28.0.1)
[✓] Android Studio (version 3.1)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[!] Connected devices
    ! No devices available

A solution that worked for me:

1. Just install plugins. Android Studio → menu File → Settings → Plugins → Browse Repositories
2. Search for "flutter".
3. Tap on Install (a dialog will pop regarding the Dart dependency. Click Yes).
4. Once the installation is finished restart Android Studio.

Now run flutter doctor:

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel beta, v0.9.4, on Linux, locale en_IN)
[✓] Android toolchain - develop for Android devices (Android SDK 28.0.1)
[✓] Android Studio (version 3.1)
[!] Connected devices
    ! No devices available

androidflutterdartflutter-doctor

I had the same issue and none of the above answers fixed it, so I went to the Flutter official GitHub repository and found the answer there. Here is the link and you have to follow all these steps.

https://github.com/flutter/flutter/issues/67986

Flutter upgrade

flutter config --android-studio-dir="C:\Program Files\Android\Android Studio"

For Mac, you can do the following as answered by Andrew:

ln -s ~/Library/Application\ Support/Google/AndroidStudio4.1/plugins ~/Library/Application\ Support/AndroidStudio4.1

flutter doctor -v

Then if the issue still persists then just shift to the beta channel and upgrade Flutter. Then it will fix it.

Flutter channel beta

Flutter upgrade

You can enable Flutter web as an optional step.

For those who still have this error, even if they have tried the solutions mentioned before, try this. It works on Windows 10, macOS, and Linux (run in the command line):

1. flutter channel dev
2. flutter upgrade
3. flutter config --android-studio-dir="C:\Program Files\Android\Android Studio"