When I load Unity5 application on android phono. It is not working. ERROR : Unfortunatly(gameName) has stopped

This is the log file.

09-01 19:25:10.588: E/Unity(4398): Unable to find main
09-01 19:25:10.628: E/art(4398): No implementation found for void com.unity3d.player.UnityPlayer.nativeRestartActivityIndicator() (tried Java_com_unity3d_player_UnityPlayer_nativeRestartActivityIndicator and Java_com_unity3d_player_UnityPlayer_nativeRestartActivityIndicator__)
09-01 19:25:10.630: E/AndroidRuntime(4398): FATAL EXCEPTION: main
09-01 19:25:10.630: E/AndroidRuntime(4398): java.lang.Error: FATAL EXCEPTION [main]

I have google it but unable to find any suitable answere.I don’t know what to do.
Thank you so much for answering.

Thanks It worked.
1.Installed android studio with sdk tools.
2. change in player setting from external to force internal.

and It worked. I am happy . Thanks.