If you're using a custom theme, and you want to use the built-in fonts, you should be inheriting from the default theme. I would check your theme and make sure you are using the correct strategy. It should look something like this:
# your custom fonts here
If you don't extend the default theme, then the path to the built-in theme should be prefixed with GEM_FONTS_DIR/. Otherwise, it will look in the wrong location.
Btw, Asciidoctor PDF 2 will support Ruby 3. Asciidoctor 1.5.x cannot support Ruby 3 because the dependencies it is locked to do not support Ruby 3.
On Thu, Feb 11, 2021 at 7:36 AM Tobi [via Asciidoctor :: Discussion] <[hidden email]
I got the following error message:
C:\Users\xxx\Documents\ms\product_descriptions\DE>asciidoctor-pdf -a pdf-themesdir=../resources/themes -a pdf-theme=pd_docs_de -a pdf-fontsdir=../resources/fonts file.adoc
C:/Users/xxx/Documents/ms/product_descriptions/resources/fonts/notoserif-regular-subset.ttf not found
This is a font in a default theme that is used as fallback. The font is not missing in the system.