Technically:

I just want to use "Dash" by "plotly", "getting started" example (https://plot.ly/dash/getting-started), but I cannot. Any assumptions?

I cannot define the error more then it is in title.

(I do not want to feed you with inaccurate assumptions. Thank you for possible answer :) )

Error was actually because of the name of my computer.

It was named "Timemachine×2", however "×" (not "x") was not an unicode character.

So I simply renamed my computer to Timemachine2 and it started to work fine.

Error was not related to the code itself.