It looks to me that the language dropdown in the advanced search for both the OPAC and Staff Client has a number of language codes either wrong or missing. For example, Armenian, Finnish, and Lao.
This seems to be the result of missing entries in the language_rfc4646_to_iso639 table, which is populated by subtag_registry.sql.
Created attachment 2700 [details] [review]
Created attachment 2715 [details] [review]
Revised proposed patch
Patches pushed, please test and close
This bug has a patch presently committed to HEAD and 3.2.x.
Please take the appropriate action to update the status of this bug.
Remember, bugs which have been resolved should be tested and marked closed, preferably by the original reporter.
A fix for this bug has been committed to the current development HEAD as well as released in 3.2.1.