samcarter
By default beamer uses a solid background for all frames. As a result, pages added with \includepdf are not visible by default because they are behind the background.

How to patch \includepdf to automatically make these pages transparent?


\documentclass{beamer}

\setbeamercolor{background canvas}{bg=red}

\usepackage{pdfpages}

\begin{document}

\begin{frame}
abc
\end{frame}

\includepdf[pages=1-1]{example-image-duck.pdf}

\begin{frame}
abc
\end{frame}

\end{document}

samcarter
One can use this little patch to use an empty background colour for all these frame:


\documentclass{beamer}

\setbeamercolor{background canvas}{bg=red}

\usepackage{pdfpages}
\usepackage{xpatch}
\xpatchcmd{\includepdf}{\begingroup}{\begingroup\setbeamercolor{background canvas}{bg=}}{\typeout{success}}{\typeout{failure}}

\begin{document}

\begin{frame}
abc
\end{frame}

\includepdf[pages=1-1]{example-image-duck.pdf}

\begin{frame}
abc
\end{frame}

\end{document}


----

**Update:**

I just added a patch to beamer ([9e3bb9](https://github.com/josephwright/beamer/commit/074e2eafc35ffa968ddf9c1920596432c39e3bb9)), so this workaround should no longer be necessary with the upcoming beamer v.3.64 or later.