Posted by Alexander Schwartz on Apr 09, 2021; 9:01am
URL: https://discuss.asciidoctor.org/Troubleshoot-missing-glyphs-pdf-from-TOC-generation-tp8585p8587.html

I addition to Dan: Copied the error message to an editor that shows non-printable characters (for example the IntelliJ editor does this).

This shows that the there is a `ZWSP' (zero-width-space).

While this is probably not something you typed in your content, this seems to be something added when creating the automatic TOC.

I raised this in https://github.com/asciidoctor/asciidoctor-pdf/issues/1909 to maybe improve the error message.