Setting beamer title page template produces empty title page

Question

I'm working on a beamer theme in which the title page should have the graphic on top. By reading beamerinnerthemedefault.sty I thought I could accomplish this by setting the title page template.

Here is an MWE:

\documentclass{beamer}
\title{Lorem Ipsum}
\subtitle{Ut molestie eros sed enim}
\author{Aspasius Protus}
\date{June 26, 2023} 
\usepackage{lipsum}
\titlegraphic{graphic}

\setbeamertemplate{title page}{
  \vbox{}
  \usebeamertemplate{titlegraphic}
  \vfill
  \begingroup
    \centering
    \usebeamertemplate{title}
    \vskip1em\par
    \usebeamertemplate{author}
    \usebeamertemplate{institute}
    \usebeamertemplate{date}
  \endgroup
}


\begin{document}
\maketitle
\end{document}

The document compiles successfully with no errors or warnings, but the title page comes out blank. Here is the log file.

I must be misunderstanding something about how \setbeamertemplate works without a predefined option. But what?

Answer 1

The titlegraphic, title, author, institute and date templates were recently added in https://github.com/josephwright/beamer/commit/5a06df06cf88917234dfe86f7e06b064808fc618 . You will need at least beamer v3.70 to use these templates in your title page.

Alternatively you could define them yourself:

\documentclass{beamer}
\title{Lorem Ipsum}
\subtitle{Ut molestie eros sed enim}
\author{Aspasius Protus}
\date{June 26, 2023} 
\usepackage{lipsum}
\titlegraphic{graphic}

\setbeamertemplate{title}{%
  \begin{beamercolorbox}[sep=8pt,center]{title}
    \usebeamerfont{title}\inserttitle\par%
    \ifx\insertsubtitle\@empty%
    \else%
      \vskip0.25em%
      {\usebeamerfont{subtitle}\usebeamercolor[fg]{subtitle}\insertsubtitle\par}%
    \fi%     
  \end{beamercolorbox}%
}

\setbeamertemplate{author}{%
  \begin{beamercolorbox}[sep=8pt,center]{author}
    \usebeamerfont{author}\insertauthor
  \end{beamercolorbox}
}

\setbeamertemplate{institute}{%
  \begin{beamercolorbox}[sep=8pt,center]{institute}
    \usebeamerfont{institute}\insertinstitute
  \end{beamercolorbox}
}

\setbeamertemplate{date}{%
    \begin{beamercolorbox}[sep=8pt,center]{date}
      \usebeamerfont{date}\insertdate
    \end{beamercolorbox}
}

\setbeamertemplate{titlegraphic}{%
  {\usebeamercolor[fg]{titlegraphic}\inserttitlegraphic\par}
}

\setbeamertemplate{title page}{
  \vbox{}
  \usebeamertemplate{titlegraphic}
  \vfill
  \begingroup
    \centering
    \usebeamertemplate{title}
    \vskip1em\par
    \usebeamertemplate{author}
    \usebeamertemplate{institute}
    \usebeamertemplate{date}
  \endgroup
}


\begin{document}
\maketitle
\end{document}