What makes latex on Mac to fail using document class apa6

Question

just installed MacTex 2023 on Mac Book Pro 2023 Sonoma 14.4 documentclass apa6 does not work as expected; TeXShop typeset: latex and pdflatexmk gives similar results

The .tex file:

% TeXShop Typeset: pdflatexmk

\documentclass[doc, 12pt, a4paper]{apa6}
\usepackage[T1]{fontenc}

\begin{document}
There is no title page and no citing!!
\section{intro}
This first paragraph following the section header should be indented as well as  the other paragraphs that are following. 
This is something that we test.

This is the second paragraph that should be indented as well; something that was 
already observed from non-apa document classes.


\end{document}

The TexShop typeset run stops at l.17 (undefined control sequence; see console output), then enter produces expected result.

I tried with documentclass [ ]{apa) this runs as expected no interruption.

{apa6} is suspicious; what could be the reason of this mismatch between {apa} and {apa6}

Console output

This is pdfTeX, Version 3.141592653-2.6-1.40.25 (TeX Live 2023) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./no-title-pag.tex
LaTeX2e <2022-11-01> patch level 1
L3 programming layer <2023-02-22>
(/usr/local/texlive/2023/texmf-dist/tex/latex/apa6/apa6.cls
Document Class: apa6 2020/01/13 v2.34 APA formatting (6th edition)
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/article.cls
Document Class: article 2022/07/02 v1.4n Standard LaTeX document class
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/size12.clo))
(/usr/local/texlive/2023/texmf-dist/tex/latex/etoolbox/etoolbox.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/lm/lmodern.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/fontenc.sty
(/usr/local/texlive/2023/texmf-dist/tex/latex/lm/t1lmr.fd))
(/usr/local/texlive/2023/texmf-dist/tex/latex/geometry/geometry.sty
(/usr/local/texlive/2023/texmf-dist/tex/latex/graphics/keyval.sty)
(/usr/local/texlive/2023/texmf-dist/tex/generic/iftex/ifvtex.sty
(/usr/local/texlive/2023/texmf-dist/tex/generic/iftex/iftex.sty)))
(/usr/local/texlive/2023/texmf-dist/tex/latex/graphics/graphicx.sty
(/usr/local/texlive/2023/texmf-dist/tex/latex/graphics/graphics.sty
(/usr/local/texlive/2023/texmf-dist/tex/latex/graphics/trig.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/graphics-cfg/graphics.cfg)
(/usr/local/texlive/2023/texmf-dist/tex/latex/graphics-def/pdftex.def)))
(/usr/local/texlive/2023/texmf-dist/tex/latex/booktabs/booktabs.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/threeparttable/threeparttable.sty
) (/usr/local/texlive/2023/texmf-dist/tex/latex/caption/caption.sty
(/usr/local/texlive/2023/texmf-dist/tex/latex/caption/caption3.sty))
(/usr/local/texlive/2023/texmf-dist/tex/latex/tools/bm.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/fancyhdr/fancyhdr.sty))
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/fontenc.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/l3backend/l3backend-pdftex.def)
No file no-title-pag.aux.
*geometry* driver: auto-detecting
*geometry* detected driver: pdftex
(/usr/local/texlive/2023/texmf-dist/tex/context/base/mkii/supp-pdf.mkii
[Loading MPS to PDF converter (version 2006.09.02).]
) (/usr/local/texlive/2023/texmf-dist/tex/latex/epstopdf-pkg/epstopdf-base.sty
(/usr/local/texlive/2023/texmf-dist/tex/generic/infwarerr/infwarerr.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/grfext/grfext.sty
(/usr/local/texlive/2023/texmf-dist/tex/generic/kvdefinekeys/kvdefinekeys.sty))
 (/usr/local/texlive/2023/texmf-dist/tex/latex/kvoptions/kvoptions.sty
(/usr/local/texlive/2023/texmf-dist/tex/generic/ltxcmds/ltxcmds.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/kvsetkeys/kvsetkeys.sty))
(/usr/local/texlive/2023/texmf-dist/tex/generic/pdftexcmds/pdftexcmds.sty)
(/usr/local/texlive/2023/texmf-dist/tex/latex/latexconfig/epstopdf-sys.cfg))
(/usr/local/texlive/2023/texmf-dist/tex/latex/apa6/config/APAamerican.txt)
./no-title-pag.tex:17: Undefined control sequence.
<inserted text> \@shorttitle 
                             
l.17 \end{document}
                   
? 
[1{/usr/local/texlive/2023/texmf-var/fonts/map/pdftex/updmap/pdftex.map}{/usr/l
ocal/texlive/2023/texmf-dist/fonts/enc/dvips/lm/lm-ec.enc}] (./no-title-pag.aux
) )</usr/local/texlive/2023/texmf-dist/fonts/type1/public/lm/lmbx12.pfb></usr/l
ocal/texlive/2023/texmf-dist/fonts/type1/public/lm/lmr12.pfb>
Output written on no-title-pag.pdf (1 page, 48472 bytes).
SyncTeX written on no-title-pag.synctex.gz.
Transcript written on no-title-pag.log.

Answer 1

If you look at the .log file you see the full error message:

./no-title-pag.tex:17: Undefined control sequence.
<inserted text> \@shorttitle 
                             
l.17 \end{document}
                   
? 

So the problem is that the class tries to use \@shorttitle, but can't find the macro. You can avoid this by specifying a short title:

\documentclass[doc, 12pt, a4paper]{apa6}
\usepackage[T1]{fontenc}

\shorttitle{text}

\begin{document}
There is no title page and no citing!!
\section{intro}
This first paragraph following the section header should be indented as well as  the other paragraphs that are following. 
This is something that we test.

This is the second paragraph that should be indented as well; something that was 
already observed from non-apa document classes.


\end{document}