When the language is set to spanish (es-ES), clicking on Help link at intranet's mainpage leads (or should lead) to the manual page in spanish for the specific version ... in this case, it leads to https://koha-community.org/manual//19.05/es/html/ which presents a "Forbidden" error. If the manual page for a specific version/language does not exists, it would be better if this error could be catched and redirected to a more useful page.
Fixed! https://gitlab.com/koha-community/koha-manual/issues/13