On IE11, setting the layout parameter modebar: {'orientation': 'v'} will break plots on IE11, with the following error:

Unhandled promise rejection TypeError: Object doesn't support property or method 'prepend'

This is likely related to this line in #3068 using element.prepend(). The bug can likely be easily fixed by using this polyfill suggested by MDN.

"Plunker" pen demonstrating the issue (graph does not display on IE11):
https://plnkr.co/edit/mnQV4RWKhAQOLUX225IL?p=preview

I had to use Plunker as CodePen et al is not compatible with IE11.