I'm currently using android 6.0 And i wanted to root it I downloaded kingoroot apk I installed it clicked one click root and it stopped at 90% and then said failed to root error 0x10db21 what do i do?
The answer is simple:
Kingoroot does not work for Android 6
The vulnerability it uses for gaining root as been fixed in Android 6 and newer. Hence rooting will not work on those devices!
Cite from the site root-apk.kingoapp.com
It perfectly covers Android 1.5 to 5.0 mainstream models from different manufacturers including Samsung, Google, HTC, Sony and else.
Hence before installing any third party app you should read the documentation before installing and running it.