Why Android Studio says "Waiting For Debugger" if am NOT debugging?

I've ran into this issue in the past and again today. In my case the problem is resolved by a device reboot. After a clean boot I can again run the application and the "Waiting for Debugger" prompt does not appear.

Please try this command to disable it.

adb shell am clear-debug-app

You can fix this issue without re-booting your device. Just go to "Android device"->"Settings"->"Developer Options"->"Select app to be debugged" / "Select debug app". It will likely be pointing to your application. Just select the option and then select "None".

Note: As mentioned, even if "None" is already selected, re-selecting "None" appears to correct the problem.

Note #2: In newer Android devices, the settings location / name might be a bit different. I.e., in my case (Android 11, Samsung) the "None" option is shown as "Nothing" instead.

Just to be clear: This is on the device, not in Android Studio (cf. very helpful comment from Regis_AG).

faster than rebooting is Just go to developer options and switch it off and on again (dont forget to check usb debugging option too), worked for me(Neuxs5).