If Outlook 2016 won’t start and get’s stuck on the processing screen all of a sudden it could be a result of a recent Office 2016 upgrade and it’s waiting for you to accept the license.  For some reason it won’t open and display the license unless you start Outlook in safe mode.  To check if this is the issue:

Outlook 2016 Won't Start

Step 1

Hold Down your Windows Key and press R

Step 2

Outlook 2016 Won't Open

In the run box type in:

outlook.exe /safe

Step 3

Select your Outlook Profile and click OK

Step 4

If you are connected to Office 365 and it asks for your credentials enter these

Step 5

Accept the license

Step 6

Close outlook and open normally

Please note that this is only one possible reason why Outlook 2016 isn’t starting.  It could also be a result of a faulty Add-In, corrupted user profile or Office 2016 needs repairing.  You may also find that you need to check your system files for corruption.