If your Outlook 2016 or Microsoft 365 Outlook desktop is not connecting, ensure that the EnableADAL key is set to 1.

Right-click or tap-and-hold the Start button and choose Run. Type regedit then press the Enter key. Registry Editor will open.

Find the registry key listed below and ensure that the value for it is 1. If it is 0, it should be changed to 1.

Registry key	Type	Value
HKCU\SOFTWARE\Microsoft\Office\16.0\Common\Identity\EnableADAL	REG_DWORD	1