Forum OpenACS Development: Re: OpenACS 5.9.1: Error in lang::util::default_locale_from_lang zh
This is the same code since 17 years and it hints on a broken configuration.
If one configures two locales (by e.g. enabling the locales "zh_CN" and "zh_TW") for the same language (here "zh") then one has to select via /acs-lang/admin/ a single locale as "default locale" for this language.
Can it be that on the installation in question, this was not done?