Org-mode export error- Wrong type argument: org-export-backend

Question

I'm trying to export an Org document to latex, but get the following error:

org-export-get-all-transcoders: Wrong type argument: org-export-backend, [cl-struct-org-export-backend nil latex ((underline lambda (o c i) (format "\\underline{%s}" c))) nil nil nil nil]

What's the way to debug it and find the error? If I create a new *.org document it can be exported to latex witout problems. Therefore I think that the reason is in the document itself, but I don't know how to look for the cause of the error.

I'm using GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.5) and have already updated all packages with M-x list-packages -> U -> x. Exporting to other formats (e.g. html) works fine.

Answer 1

Despite doing M-x list-packages -> U -> x, org hadn't been updated (probably because it was not installed through melpa). After upgrading org the error disappeared.