If you have bad HTML which means an accessibly tagged PDF/UA-1 document then you get an error like this:

prince: error: table header cell has no associated subcells on page 580
prince: error: not identifying as PDF/UA-1 due to problems in structure tree

However an untagged PDF is still created.

It would be good if you could optionally force the generation to fail here with an exit code of 0, so it's more apparent you have an issue, for those of us that do not want to fall back to an un-tagged document.

Good point, I think we need to extend the existing fail-safe options for this.

In the latest build we have added two new options: --fail-pdf-profile-error and --fail-pdf-tag-error, along with a generic --fail-safe option that enables all of the fail safes for convenience.