First, clear the cache. A massive amount of cached data can cause problems. Close all apps. Go to Settings -> Apps and use the top tab to show running apps. Force Stop each running app. Now, go to Settings -> Storage - Cached Data. It will ask if you want to clear. You do. (This is for Jelly Bean 4.2 and later Android versions.) Right now, my cached data is 470MB, a lot. This can clear many problems and saves a bunch of data space, anyway. See if the phone app can keep running.
If that doesn't work, and IF you have access to your phone application in your Settings->Apps list, uninstall it and reinstall from scratch. You may not have access, though. It may be a native function of the device.
If that doesn't work. You've updated, so now try rebooting the device. Reboot varies with device. On my Droid Razr Maxx HD, it involves holding down the volume rocker and the wakeup switch. Web search for how to reboot your device. This may fix many problems that otherwise would appear to be app problems.
It's a good idea to do a web search for the name of your phone and any such problems on your device. The support forums on your service provider's web site will likely have a number of posts if there is a current problem. If you see that others are suddenly having the same problem, it may mean an update was buggy, and the fix didn't work, and another update is on its way.
And it's worth a call to your provider's tech support. They also will likely have heard of any new problems, and if nothing else works, they can help you through the ultimate approach, which is wiping the phone and starting with a new Android load.
