Android Studio 3.0 Unsigned Apk Not Installing
Answer : Looks like we can not directly use the apk after running on the device from the build->output->apk folder. After upgrading to android studio 3.0 you need to go to Build -> Build Apk(s) then copy the apk from build -> output -> apk -> debug Like this - Fist Click On Build Icon on android studio after that click Build APK(s) then Generate APK the copy Apk. It is working perfact.