For clarification, the root cause is a ' in the french translation, which breaks some javascript code. The code is fixed to prevent this, but since it involves other changes, the easiest fix the moment is to remove the quote from the translation file. This can be done by running the following on the server via SSH:
sed -e "s/\"errorIncorrectCredentials\": \"Nom d'utilisateur ou mot de passe incorrect\",/\"errorIncorrectCredentials\": \"Nom dutilisateur ou mot de passe incorrect\",/" -i /home/yellowtent/box/dashboard/dist/translation/fr.json