If your GitHub Pages code uses the highlighter tag with an invalid language identifier, your GitHub Pages site will not build.
If your GitHub Pages site fails to build because you specify an invalid highlighter language, you'll get an email with this message:
Subject: Page build failed
The page build failed with the following error:
The highlighter language identifier `invalidlanguage` is invalid.
You will only receive an email if outbound email support is enabled on your Enterprise instance. For more information, contact your site administrator.
Troubleshooting invalid highlighter language errors
Tip: We strongly recommend running Jekyll locally so you can easily debug and fix build errors before pushing to your GitHub Enterprise instance. To learn more about troubleshooting options, see "Troubleshooting GitHub Pages builds."
Rouge is Jekyll's default syntax highlighter and is compatible with the Pygments highlighter. Ensure that:
- you're using Rouge's syntax highlighting correctly, follow the guidelines in "Using syntax highlighting on GitHub Pages."
- your site's configuration is set up correctly for Rouge, see "Fixing highlighting errors."

Formed in 2009, the Archive Team (not to be confused with the archive.org Archive-It Team) is a rogue archivist collective dedicated to saving copies of rapidly dying or deleted websites for the sake of history and digital heritage. The group is 100% composed of volunteers and interested parties, and has expanded into a large amount of related projects for saving online and digital history.
