This article shows you how to open Outlook in Safe Mode if it won't open properly or if you can't open some Outlook windows. You should also try Safe Mode if settings get stuck when you make changes, you suspect a recently installed extension contains malware, or features or windows are behaving strangely. Instructions apply to Outlook 365 and Outlook 2019-2020.

To open Outlook in Safe Mode, hold down the Ctrl key and select the Outlook shortcut. In the warning dialog that appears, confirm that you want to open Outlook in Safe Mode by selecting Yes.

Another way to open Outlook in safe mode is through the command prompt:

Press the Win+R keyboard shortcut to open the Run dialog box. Or type run in the Windows search box and press Enter.