Green Scren while open world

I open my world that i build for a year.then last night i open it then about 30second playing the green scren pop up.i try restart my tab(Samsung glaxiy 2) than it also same.itry duplicate world it also same .i try downgrade from 0.12.3 to0.12.2 then 0.12.1 i get it same ...why this bug NEVER been FIX?!!!