Session 'app': Error Launching activity

Question

After the Android Studio 2.0 update while the gradle build finishes I get this :

Session \'app\': Error Launching activity .

It prevents the app from starting

Answer 1

Just Run --> clean and rerun , In my case it helps. Prompts automatically like following message

would you uninstall already installed activity with same name

if activity is already installed first uninstall it and make project ready after installing app.