For some reason your iPhone calendar keeps crashing. You tried killing the app, rebooting the the iPhone a few times, but to no effect. The only thing left to do is to call Apple Support (ha! good luck with that!) or a friend or perform a full restore using iTunes on your computer.
But wait! there’s one more thing left to try: goto search (the so called Spotlight search) by swipping to the far left of your screens, and try to search for any calendar event. If you’re lucky it should come back with some results and when you tap onto an event it should launch the calendar app nicely. And every time after that.
If your out of luck, then start calling your friends, search Google or just get ready for that full iPhone restore.
This tip was discovered by my smart wife, whom we should thank.