Error Build, -s assertion=1

Hello guys !

I’m trying to make a cook of a scene on html format but it does’nt work (error here : https://answers.unrealengine.com/questions/177170/cook-html5-error.html )
at the end of this error it says I should cook with -s assertion=1 to see a more complete log.

But I don’t know where I shall put this, does anyone have an idea?

Thanks in advance

Denis