I don’t have a license for Microsoft To-Do app But you can still report errors and different situations to Microsoft and improve the application experience for yourself and other users. Although, Microsoft tracks and records application crashes automatically.

A further step could be testing the application on a similar device as yours. If the application keeps crashing, you can try uninstalling it and then install it again. If you think everything else is functioning fine and you’ve received this message due to an error, you can contact the IT administrator or write to Microsoft about it. Until unless you toggle the switch ON, your users will not be able to access any of the To-Do’s features.

If you are the admin, you can enable this feature by going to ‘ To-Do Preview’ section in the ‘ Services & Add-Ins’ page.

If you see this error message when you try to access the application, then To-Do has not been enabled by your organization’s admin. Web: Latest version of Safari, Internet Explorer 11, Chrome, Edge or Firefox Microsoft To-Do app To-Do is not enabled.

Microsoft to do not working