>>> "Josiah" == Josiah Schwab <jschwab@gmail.com> writes:

   > Hi Uwe,
   >> Now I took the example
   >> https://orgmode.org/manual/A-Beamer-example.html#A-Beamer-example
   >> 
   >> And wanted to export it to beamer but obtained the message 
   >> user-error: Unknown LaTeX class ‘beamer’

   > This sounds to me like you are using the latex exporter, rather than the
   > beamer one.

   > After

   >   (require 'ox-beamer)

I have this set.
   > then

   >   C-c C-e l b

   > works well on the example for me.
Not for me.

I have to open ox-beamer and go to 

(unless (assoc "beamer" org-latex-classes)
  (add-to-list 'org-latex-classes
	       '("beamer"
		 "\\documentclass[presentation]{beamer}"
		 ("\\section{%s}" . "\\section*{%s}")
		 ("\\subsection{%s}" . "\\subsection*{%s}")
		 ("\\subsubsection{%s}" . "\\subsubsection*{%s}"))))

And run eval-last-sexp

Then it works.

So there is something fundamentally wrong here.

As I said I am using the latest org/emacs master.

Sounds like a bug