If your GitHub Pages repository contains a post with an invalid date, your GitHub Pages site will not build.

If your GitHub Pages site fails to build because of a post with an invalid date in the filename, you'll get an email that looks like this:

Subject: Page build failed

The page build failed with the following error:

"The post `2012-02-30-time-is-an-illusion.md` does not have a valid date in the filename."

And if your GitHub Pages site fails to build because of a post with an invalid date in the YAML front matter, you'll get an email that looks like this:

Subject: Page build failed

The page build failed with the following error:

"The post `2012-02-30-time-is-an-illusion.md` does not have a valid date in the YAML front matter."

Troubleshooting post date 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 you're using proper date formatting for filenames with dates and any date values in the YAML front matter of your files. Dates must be formatted as YYYY-MM-DD HH:MM:SS for UTC, and must be actual calendar dates.
  • If you specify a date format in your _config.yml file, make sure you format it correctly. To specify a time zone with an offset from UTC, use the format YYYY-MM-DD HH:MM:SS +/-TTTT. For example: 2014-04-18 11:30:00 +0800.

Once you've fixed all post date errors, you will need to commit your changes and push to your GitHub Pages repository again to trigger another build on the server.