I recently updated my org-mode git repository (for a long time I've had an older git version that I was using), and I am now having problems when doing latex exports.
I bisected with git to find that the "problem" starts with this revision: commit 54318add34f09ff39d3fd034a4c1a89f60fd8759 Author: Nicolas Goaziou <m...@nicolasgoaziou.fr> Date: Tue Feb 3 16:16:54 2015 +0100 Change export block syntax It seems that #+begin_latex is no longer supported, and that when using it, it results in escaped latex comment symbols (e.g. \% in the tex file instead of just %), as well as \begin{latex} and \end{latex} in the exported code. If it is no longer supported, then it is important that the org-mode documentation be updated (see e.g. http://orgmode.org/manual/Quoting-LaTeX-code.html ), since those using the latest release will have trouble exporting using the old syntax.