Call to undefined function _i18n_get_lang

I get this error:

Fatal error: Call to undefined function _i18n_get_lang() in /srv/adulmec.ro/corporate/sites/all/modules/contributed/taxonomy_context/taxonomy_context.module on line 414

when I go to

taxonomy/vocabulary/3

for one of my vocabularies. i18n is installed and most of its modules are enabled.