Unknown tag 'liquid' despite it being a valid tag

I’m using the liquid tag in an include so that I can do logic easily but whenever I try to build Jekyll keeps complaining that it’s an “unknown tag” and a “syntax error”. Is it not supported by Jekyll?
It’s written right here that it’s a real thing Template – Liquid template language ! What do I do… I really need it…

Could you please minimally provide the following?

The fully qualified file name and location and the code block?

Ideally you share a link to your repo and a link to the file.

It isn’t explicitly mentioned in the docs, but Jekyll currently uses Liquid 4 (see Gemspec below). So any Liquid 5+ tags cannot be used. The Liquid documentation marks all 5+ features, so you can avoid them. As you discovered the new templating tags of liquid, echo, and render are all only 5+.

I believe the new tags are just for convenience. Liquid 4 has the same functionality, just with a bit more syntax. If you have an example, we might be able to help translate from 5 to 4.

Awh, thanks for telling. I converted it myself since I don’t really mind, it was just for convenience.