Alt+Enter stopped working for Dart files in IntelliJ

Here it is. You are welcome.

go to File> Settings> Editor> Intentions and confirm the Dart Analysis Server.

I had the same issue. This solved it for me:

1. Switch to a different flutter channel. If you are on stable then go to beta or vice versa. Instructions on switching channels at this link: https://flutter.dev/docs/development/tools/sdk/upgrading

2. Run flutter upgrade

3. Restart your IDE.

4. Check to see if the lightbulb (or ALT-Enter or Option-Return) is now active.

5. Switch back to your other channel and repeat steps 2 and 3 above.