When launching Outlook you may receive the following error.
This error could occur from a number of different reasons.
Disable the Add-ins
One possibility–and always the first thing to check–is that an Outlook add-in could be causing the error. To determine if this is the root cause open outlook in Safe Mode.
To do this, hold the CTRL key on your keyboard while clicking the Outlook icon. You will receive a prompt asking whether you want to open Outlook in safe mode. Click Yes.
Outlook will then launch with all add-ins disabled. Furthermore the reading pane and any toolbar customization will be disabled. You can then navigate to File >> Options.
Once in options select Add-Ins. From here you can see all add-ins that load when Outlook is opened in normal mode. To disable an add-in click the Go… button.
From the Add-Ins dialog you can deselect an add-in to disable it. Click Ok then restart Outlook. You can repeat this process until you find the add-in preventing Outlook from starting