If Outlook now closes properly, you can enable your add-ins one-by-one (restarting Outlook after each one) to find out which add-in prevents Outlook from closing. To find out if your issue is being caused by an add-in, disable them all and see if the issue goes away. Various add-ins hook into Outlook in such a way that closing Outlook on its own has been made impossible. Solving shutdown issues caused by add-ins Your data file for issues in the background. The gears icon indicates that Outlook checks

Error message about an add-in when starting Outlook again.

In this case, in order to be able to open Outlook again, you’ll have to start it with the /resetnavpane switch.

This can result in an Outlook startup error saying Cannot open the Outlook window.

Navigation Pane corruptions or resets.

outlook.exe is still running on the Processes tab in Task Manager (accessible via CTRL+SHIFT+ESC or by right clicking an empty spot on your Task bar and choosing Task Manager).Not being able to switch Mail Profiles (when using more than 1 mail profile in Outlook).The Outlook icon is still in the Notification Area with an X in it ( ).Not being able to backup your pst-files.Gears icon in the bottom right corner in Outlook.This file is being checked for problems.” Error “The data file was not closed properly.Error message prompting you to run the Inbox Repair Tool (scanpst.exe).AutoComplete / AutoSuggest cache becoming corrupted and Outlook no longer offering you email addresses anymore when addressing a message.Outlook is not able to start anymore after you have closed it and you are only being able to open Outlook again after restarting the PC.Outlook shutdown issues are not always directly apparent but may surface via other errors or issues such as

After you’ve solved your shutdown issue.

Solving shutdown issues caused by applications.

Solving shutdown issues caused by add-ins.

How to recognize Outlook shutdown issues.

Once this troublesome add-in is disabled or updated or the other application is closed, the problem will be gone and Outlook will close normally again. At that time, you’d usually see the outlook.exe process still running in Task Manager as well. Practically always this is caused by an add-in or another application which integrates with Outlook. It isn’t very common that Outlook doesn’t close on it’s own.

Outlook task manager