If you’re facing the following error when trying to publish a GitHub Pages site:

Your site is having problems building: Unable to build page. Please try again later.

The solution is pretty simple, as quoted from sethclydesdale from github.community

If you’re not using Jekyll 106 to build your website, sometimes GitHub pages will mistake certain characters, specifically curly braces, as jekyll objects, tags, etc. causing your page build to fail. If you’re just using static HTML pages (which is what it looks like to me), the easiest and quickest fix would be to disable Jekyll processing, which can be done by creating a file named .nojekyll in the root of your pages repository.