I just had this exact same problem, but AFTER it was working
It happened because I had to reset the gh-pages branch. So I
Then I had a script create an orphan branch gh-pages, populate it, and push it. Before this, everything worked without /index.html, but after, I had to add /index.html. I must have triggered a bug by accident.
The fix was was go into the settings and change the GitHub Pages Source branch to master, then back to gh-pages. This toggle was able to get around the bugged state I found myself in and everything is good again.
Had the same error.
Solved by adding language property to html tag:
Or maybe because it just created another build?
- Create a file named "_config.yml" with "theme: none" written inside of it (all without quotes) into the home/main directory where your "index.html" file is placed.
Github Pages is searching for a configuration file for theme (if required) which is what probably does not exist in your case. Try this method, it should work.