android - An Activity launched on start of my app unintentionally -

i'm not sure if i'm missing obvious, having strange bug in android game.. working longest time well. , i'm not sure if it's related fact yesterday upgraded android 5.0 -> 6.0.

i have 3 activities (main, settingsactivity, rankingsactivity) in app. naturally, main has this:

<intent-filter>     <action android:name="android.intent.action.main" />     <category android:name="android.intent.category.launcher" /> </intent-filter> 

however, reason app crashes in rankingsactivity's oncreate()-method. there exactly 1 place (within button click) start rankingsactivity via intent, , commented line out.

i know cause of crash: it's start rankingactivity @ point.

what possibly cause rankingsactivity launched upon start of app? i've uninstalled whole app, , cleared data.