2015-10-15 18:54 GMT+02:00 Fabrice Popineau <fabrice.popineau@gmail.com>:

>
>
> 2015-10-15 10:37 GMT+02:00 Nicolas Goaziou <mail@nicolasgoaziou.fr>:
>
>> Fabrice Popineau <fabrice.popineau@gmail.com> writes:
>>
>> > At some point LaTeX reported an error on some frame heading.
>> > I wrongly inferred it could be the label.
>>
>> It would be nice to investigate about this error, it it persists.
>>
>>
> Beamer is very bad at reporting errors at their true origin.
>
> Actually, I had 2 errors.
>
> First all my Org->TeX files use Babel, and they doesn't seem to cope well
> with colons in labels.
> (org-lint even reports about it)
> Unfortunately, the default naming scheme for internal labels is using
> colons.
> Hence I wanted to use my own labels.
>
> (Actually, I don't understand what prevents "beamer 2015/01/05 3.36" to
> use colons in
> labels. I thought that this problem has been solved around beamer 3.30.)
>

Oh! I got it.

The problem is that beamer expects braces around a label with colon when
you setup the label
but *not when you ref it* :

\begin{frame}[label={sec:orgheadline1}]{Frame 1}
bla bla bla bla bla bla bla bla bla bla bla bla
\end{frame}

\againframe{sec:orgheadline1}

The braces at setup are required by the keyval package which is used to
parse the options.
However, the label is called sec:orgheadline1 and not {sec:orgheadline1}.
But at the moment, ox-beamer outputs :

\againframe{{sec:orgheadline1}}

I fixed it unintentionally by using my own label without colon.

So basically you need this:

diff --git a/vendor/org-mode/lisp/ox-beamer.el
b/vendor/org-mode/lisp/ox-beamer.el
index 24dcf19..75b51df 100644
--- a/vendor/org-mode/lisp/ox-beamer.el
+++ b/vendor/org-mode/lisp/ox-beamer.el
@@ -621,7 +623,7 @@ as a communication channel."
                                     (org-export-resolve-id-link link
info))))
                      ;; Now use user-defined label provided in TARGET
                      ;; headline, or fallback to standard one.
-                     (format "{%s}" (org-beamer--get-label target
info)))))))
+                     (format "%s" (org-beamer--get-label target info)))))))
        ;; Case 2: Creation of an appendix is requested.
        ((equal environment "appendix")
        (concat "\\appendix"


Fabrice