Region for the footer not working, but the header is working I have the following regions set up in my *.info.yml file:

name: Test
type: theme
description: 'Theme'
base theme: stable
core: 8.x
regions:
  header: 'Header'
  content: 'Content'
  footer: 'Footer'
libraries-override:
  system/base: false


In page--front.html.twig, I placed {{ page.header }} where I wanted the header to be, and noticed via Twig Debugging that Drupal was expecting a file named region--header.html.twig.  Great!

So, similarly, I did this for the footer.

{{ page.footer }} and region--footer.html.twig ... but it does not work!  Twig Debug's comments do not reveal any hook for the footer at all.

What am I doing wrong?
Regions are only rendered by default if they contain blocks (of which at least one must have content).

You can check whether the Footer region has blocks assigned to it by visiting the Block Layout admin page at /admin/structure/block. If you see the No blocks in this region message under the Footer block, you know that's the problem.