When I try to load a translation from
https://pt.wikipedia.org/wiki/Special:ContentTranslation?page=Puiseux+series&from=en&to=pt&targettitle=S%C3%A9ries+de+Puiseux
I get
VM161:75 Uncaught TypeError: Cannot read property 'length' of undefined at Template.init (<anonymous>:75:6128) at new Template (<anonymous>:75:5649) at Object.TemplateTool.static.processTemplate (<anonymous>:94:68) at TemplateTool.static.processBlockTemplate (<anonymous>:95:944) at fire (load.php?debug=false&lang=pt&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1b46sjy:46) at Object.fireWith (load.php?debug=false&lang=pt&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1b46sjy:47) at Object.fire (load.php?debug=false&lang=pt&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1b46sjy:176) at ContentTranslationLoader.restoreSection (<anonymous>:8:53) at ContentTranslationLoader.restore (<anonymous>:5:74) at <anonymous>:3:126
The problem also happens with Firefox.