Flutter App stuck at "Running Gradle task 'assembleDebug'... "

Here is solution in my case.

1. Open your flutter Project directory.
2. Change directory to android directory in your flutter project directory cd android
3. clean gradle ./gradlew clean
4. Build gradle ./gradlew build or you can combine both commands with just ./gradlew clean build
5. Now run your flutter project. If you use vscode, press F5. First time gradle running assembleDebug will take time.

PS: Delete gradle in case of all that steps don't work

flutter run -v showed that I was stuck on

Downloading https://services.gradle.org/distributions/gradle-5.6.2-all.zip

This was going to take hours, as for some reason the download speed was ~10kB/s on a decent DSL connection.

Solution:

1. Interrupt gradle build
2. Download the required gradle zip from a fast mirror. e.g. https://distfiles.macports.org/gradle/gradle-5.6.2-all.zip
3. Copy gradle-5.6.2-all.zip to C:\Users\ <MyUsername>\.gradle\wrapper\dists\gradle-5.6.2-all\9st6wgf78h16so49nn74lgtbb (of course the last folder will have a different name on your PC)
4. flutter run and voilà.

In my case, Windows Firewall was causing this problem. After I disabled it temporarily the problem was gone. Worth giving it a try. Good luck!

If you are on Windows: try adding firewall exceptions to your Android Studio.

1. Go to:

   Control Panel\System and Security\Windows Defender Firewall\Allowed apps

2. Hit the button:

   Allow another app

3. Add your new firewall exceptions:

   studio.exe and studio64.exe

I hope this can be useful for you too.