Some theories - – the food may have been trying to break out, you should securely cover whatever you put in it from now on – your oven has a thing against carbs, try fine meat products – it’s haunted And some theories that may actually be true - – the thermostat may be woefully off or broken and your oven could be running much hotter than it should be, did the food you cooked come out normally, or was it extra crispy? – the door itself may be “tweaked” and is preloading the window with some stress, a little heat may be all it takes to make it crack… was the new door tough to install? maybe the hinge is askew? This could be due to anything from it getting bumped at some point to the foundation of your home settling… Most ovens have double glass on the front, one pane inside and one out with a decent gap in between. Is your oven the same? Are they both shattering or just one? That may help you locate the cause.