My android game is crashing on stock nexus 4 running Android 5.1.1 . My unity versioin 4.6.7p2 ? Its running on other android devices.I've attached logcat.But i don't understand it.Need urgent help

Whats error at NullReferenceException: Object reference not set to an instance of an object I/Unity (29302): at SpawnScript.FixedUpdate () ?

I have made a game object which not yet set to another object..but it is set as soon as player hits play button.I don't think this is the error because in every other phone the game works

"it is set as soon as player hits play button" - it obviously isn't being set, because if it was you wouldn't be getting an error. You really need to eli$$anonymous$$ate all errors and warnings before deploying your game to a device.

yeah i know..But i don't understand one thing why it works on every other android phones.but not on nexus 4

You're trying to access an object that doesn't exist, which is leading to undefined behaviour. Having identified a fault in your code, you should fix it, then test again.