Generic "Page build failure"

At some point my blog had a working theme. I tried to add a remote theme and it never worked, so I had removed the theme from my _config.yml entirely. I just revisited to try to out themes again, but now I can’t get anything to build at all. I tried reducing the file to nothing, or gone entirely, or just with a theme added via the configurer, and all produce a generic error & email:

The page build failed for the `master` branch with the following error:

Page build failed. For more information, see

I assume I corrupted something, but I have no idea what.

You have made a mistake with the post_url tag in this commit:

You should pass the entire base filename of the post not just the title slug.

- (See {% post_url springmvc-jsr303-websphere%}.)
+ (See {% post_url 2018-05-23-springmvc-jsr303-websphere %}.)


But, wow, that makes the entire build fail, and doesn’t even tell me why? Guess I should use regular hrefs instead of post_url, eh?

{% post_url ... %} , {% link ... %} and {% include ...%} are designed to fail fast and output a message to the terminal. You would’ve seen a message in the terminal window if you built the site locally first.

Why GitHub Pages doesn’t include that message in their report and email is beyond my understanding.