Undefined control sequence \uline in exporting org-mode with underline markup to PDF using xelatex

Question

For the following sample,

#+LATEX_CMD: xelatex
#+LATEX_HEADER: \usepackage{xltxtra}
#+OPTIONS: ^:nil

This is a _test_

The export to PDF uses xelatex would produce the following error:

! Undefined control sequence.
l.28 This is a \uline
                     {test}
? 
! Emergency stop.
l.28 This is a \uline
                     {test}
No pages of output.

If I use pdflatex then there is no such error. (I have to use xelatex for exporting text with Chinese.)

What would be the solution with xelatex?

Answer 1

The LaTeX command \uline is defined in the LaTeX package ulem. You can load that package during PDF export with the following line in your org-file.

#+LATEX_HEADER: \usepackage{ulem}

Fine if that already helps. Nevertheless a problem of ulem with XeLaTeX is reported at golatex.de. Following that thread the workaround would be:

#+LATEX_HEADER: \usepackage{ulem}\usepackage{fixltx2e}

Note that in org-version 9.1.6 ulem is already present in org-latex-default-packages-alist as entry ("normalem" "ulem" t).

If you have already that or a newer version of org-mode then it might be that you have modified org-latex-default-packages-alist and that list is not upgraded for you.

Otherwise you could just upgrade to the newest stable version of org-mode from melpa. If you do not like to upgrade for any reason maybe you can add the ulem entry to org-latex-default-packages-alist.