Multilang-site override a option of JCategories that cause a SQL error
From Joomla! Documentation
In Joomla! 3.4.2 we improved the multilingual code. But for now if a component don't have disable a specific option in JCategories that gets overwritten on multilinguage sites.
A SQL error at some extensions that disable a option in JCategories but only on multilingual sites.
Example PhocaGuestbook: http://www.phoca.cz/forum/viewtopic.php?f=2&t=34526
Issue Report & Patch: https://github.com/joomla/joomla-cms/pull/7303
This pertains only to Joomla! version(s): 3.4.2
What is the cause
Just a SQL Error after the patch it should gone.
How to fix
Apply the patch https://github.com/joomla/joomla-cms/pull/7303.diff. This will be fixed in Joomla 3.4.3 that comes soon.