'Wayfinder' navigation problems

The problem

I have been bitten by this several times, and it is always because I have forgotten a simple golden rule when creating a site template.

I create site content where there are documents acting as containers with other content inside them.  The site is configured to use friendly urls, and both the containers and sub documents have url aliases.

The first click on a menu entry which is a container works ok.  Subsequent menu clicks fail, and a wrong URL is seen in the browser's address bar.  This will typically have a url alias contatenated onto itself several times in the displayed address.

The solution

I have forgotten the golden rule that there MUST be a '<base href=' tag in the head section of the site template.

e.g.

<base href="http://www.mysiteaddress.xyz/" />

Wayfinder generates urls which are relative to the site base address. Without the browser being told that address, the navigation breaks down.