>>> "Ken" == Ken Mankoff <mankoff@gmail.com> writes:

   > On 2018-12-16 at 10:16 -0800, Uwe Brauer <oub@mat.ucm.es> wrote:
   >> So the problem is in my init file and I am quite sure that it has to
   >> do with the following lines in my custom- file
   >> 
   >> '(org-latex-classes

   > What is the full line here? Is this a "setq"?

No it is not a setq, it is a 
(custom-set-variables

Which I did not copy.