I've seen this happen for a few reasons with various fixes:
It may happen after disabling an app, usually if you force close it before disabling it. If you've disabled anything, try turning it back on, one by one if you disabled several, until the error is gone.
It can also happen if you use Clean Master or similar apps to uninstall supposedly unnecessary apps. Reinstall such removed apps. Uninstall Clean Master.
Sometimes a contacts sync problem will cause this even after contacts have apparently synced again successfully. Clear the contacts app cache and data, then resync. *Be sure to back contacts up first, just to be safe!*
Facebook can cause this. Clear cache and data, then uninstall/reinstall.
There may well be other causes, but these are ones I've seen (and can remember).