If your GitHub Pages code contains Markdown errors, your GitHub Pages site will not build.
If your GitHub Pages site fails to build because of invalid Markdown, you'll receive an email that looks like this:
Subject: Page build failed
The page build failed with the following error:
The file `example.md` contains markdown errors.
Troubleshooting Markdown errors
Tip: We strongly recommend running Jekyll locally so you can easily debug and fix build errors before pushing to GitHub. To learn more about troubleshooting options, see "Troubleshooting GitHub Pages builds."
Make sure the file mentioned in the email uses valid Markdown syntax. See "Getting started with writing and formatting on GitHub" for more help or the Daring Fireball Markdown guide for a more complete guide to Markdown syntax.
Once you've fixed any Markdown errors, you will need to commit your changes and push to your GitHub Pages repository again to trigger another build on the server.