We could not load the add-in because Internet Explorer is disabled.

Symptom

When trying to launch the Office 365 add-in in Outlook for Windows, you get the error message below:

Solution

This error message occurs, when you have removed Internet Explorer from Windows (Windows 7, Windows 8, Windows 10). In this case, the add-in will not work in Outlook. Outlook uses Internet Explorer 11 to display the UI, so it's a hard requirement for any kind of add-in to work. To re-install Internet Explorer, please follow the guide on the bottom of this help page: How to use Internet Explorer