# PDF/A-1b: Adobe Preflight verification passes and veraPDF fails

I'm having the following LaTeX code called test1b:

\documentclass{article}

\usepackage[a-1b]{pdfx}

\begin{document}
Bla bla ...
\end{document}


Using pdfLaTeX I can generate a PDF which claims that it is PDF/A-1b.

If I verify this PDF with Adobe Preflight it passes.

If I use veraPDF V1.10.6 to verify the PDF it fails and I get the following error:

See Rule 6.3.4-1. How can I solve this problem?