Ota update problem on Android one spice dream uno

I'm using a spice dream uno Android one running 5.1.1 lollipop.I recently got a security patch (18 mb).
It won't install properly and just shows error.. My phone is unrooted..I have also tried wiping cache.
It also didn't help.. So guys pls suggest me something.. I really don't like to do a factory reset.. Thanks in advance.