View contextual filter not working inside Panels I have a view with a contextual filter of type "Raw value from URL".  This block view works fine in the page footer. But when added inside Panels &amp; Page Manager, the view stops working. Hence it seems that Panels is somehow blocking the view from being able to access the URL.

As a test, I have the view in Panels and in the footer on the same page, and the footer view displays fine, but the Panels view does not, giving me a "Page not found" error.  

I read I need a "context" in Panels to pass information to a view.  I also read that view contextual filters that use URLs don't need contexts in Panels, so I'm finding conflicting information.

Every time I try to create a Panels context, I get an error, mostly since I have no idea what to enter into the form fields.

The view looks for a value in the URL, such as /puppies/10, where 10 is the node of the puppy. Then the view will only show information for that puppy.

Most of the information out there is for Panels on Drupal 7, and there seems to be enough of a difference that I can't figure it out for Drupal 8.
I had the same problem and figured it out. Enter /your/path/{parameter} for your page path and the Page Context link will change to a Page parameter link. You can use any word for {parameter}, it is just a variable name. You specify the type of the parameter under Page parameter. It would have saved everyone an enormous amount of time, if this was included in the instructions underneath the path field.