I'm not suggesting the person that overruled you is free from blame. I absolutely am suggesting that if you are in that situation you have to take your lumps and accept it, not deflect ("it's not my fault because Tom told me we had to use xyz"). The other person who is at fault should also be accepting blame, but it's not your job to render the blame. In fact, you're never at all the arbiter of blame with anyone lateral, above you, or (usually) anyone in another department; it's always your fault.

Your boss told you to use xyz technology? You (and others, if necessary) should have convinced him otherwise. If you can't and his decision is a bad one, you have to be the one that says no. That's right -- it's your job on the line, not his. If you signed up to be vp of IOS software, you're in the wrong if something is broken in IOS software. That's why you need to learn to say "no", not only to clients, but to coworkers as well. If that's absolutely not possible, it's time to put on your big boy/girl pants and take the blame because you couldn't fix a problem that you knew existed.

If you're in a situation where different people are telling you different things, then it sounds like you get to decide the specific implementation. It's even probable that those different people telling you different things are really giving you their unsolicited opinion, rather than micromanaging your career.

I think it's cowardly to avoid responsibility for what you sign your name to.