Program not uploaded correctly using Arduino 1.6.12

I am currently using Arduino 1.6.12 and tried uploading the program in a circuit. This circuit with the same program has been tested earlier with Arduino 1.6.9 but now when I uploaded the program using 1.6.12 version my circuit behaves very uncertainly, why is this happening please help!

I am using arduino on windows 7.

but now when I uploaded the program using 1.6.12 version my circuit behaves very uncertainly

Well, my crystal ball needs some polishing ...
What circuit, what sketch, what "uncertainly"?

Please post the whole sketch (not just snippets) and a schematic (not fritzing, we hate fritzing here), and describe what has changed in the behavior.

I have seen no issues involving the behavior of the uploaded code (some in moving from 1.6.9 to 1.6.12 - but there are very significant changes under the hood in the form of Link Time Optimization, which reduces the compiled size of the sketch by 10~20% in most cases.