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GitHub Pages Jekyll build failed because a date is not a valid datetime

Date is not a valid datetime

GitHub Pages could not build the Jekyll site because a page or post contains a date value that Jekyll cannot parse as a valid datetime.

Date is not a valid datetimebuild errors

Observed message

Date is not a valid datetime

Why it happens

  • A post or page front matter contains an invalid date value.
  • The date format does not match what Jekyll expects.
  • A malformed or incomplete timestamp is being parsed during the site build.

How to fix it

  1. Review front matter on posts and pages for invalid or malformed date values.
  2. Use a valid date or datetime format supported by Jekyll.
  3. Rebuild after correcting the file that contains the bad timestamp.

Official reference

GitHub Docs: Troubleshooting Jekyll build errors for GitHub Pages sites

Related errors

File does not exist in includes directoryGitHub Pages Jekyll build failed because a file does not exist in the includes directoryFile is not properly UTF-8 encodedGitHub Pages Jekyll build failed because a file is not properly UTF-8 encodedInvalid post dateGitHub Pages Jekyll build failed because a post has an invalid post dateInvalid highlighter languageGitHub Pages Jekyll build failed because an invalid highlighter language was used

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GitHub Pages date is not a valid datetime: causes and fixes | Error Atlas