It seems that you are using Version 2.0 of date-fns, which is still in alpha (development) status currently.
What functions are available and how they work still seems to change frequently. For example, while in version v2.0.0-alpha.26 toDate()
can handle string parameters, it cannot do that any longer in version v2.0.0-alpha.27. There is a new parseISO()
function instead.
This should work now:
format(parseISO('2019-02-11T14:00:00'), 'MM/dd/yyyy')
However, while version 2 is still in beta, I would suggest using the stable version 1.x for now.