Have you ever opened up the Windows 10 Mobile Outlook calendar app and have it close on you 10 seconds later… and no matter how many times you open the app, it just keeps closing down on you?
This might also happen when you open the Windows 10 Outlook Mail app as well. (I believe this actually applies to both Windows 10 Desktop & Windows 10 Mobile.)
CAUSE: Do you have an Office 365 email account? This might apply to Exchange (on-prem) account users as well but I had this problem and near as I can tell, something in my local Outlook database for the Office 365 account got corrupted on my Windows 10 Mobile phone.
I’ve read stories about this having to do with some sort of malformed HTML in an Calendar or Email object that it was reading/processing and the result was an errorless crash of the respective app.
SOLUTION: The solution is simple.
If all went right, you should be able to open your calendar and email without it crashing on you while you’re using it.