Follow-up of Bug 36221. In Koha/ILL/Backend/shared-includes/shared.js '" name="custom_key" placeholder="'+__('key')+'">' + ' ' + '<input type="text" id="custom-value" name="custom_value" class="' + ( opac ? 'form-control input-fluid custom-field-input' : '') +'" placeholder="'+__('value')+'"> ' + '<button type="button" class="btn btn-danger btn-sm ' + 'delete-new-field">' + '<span class="fa fa-trash-can"></span> ' + __('Delete') + [...] $('#custom-warning').text(__("The name '%s' is not permitted").format(val)).show(); ------- This will need to be tested once bug 38340 has patches. For now stuff is not translatable but once it is, it's expected the JS can break if the translated string contains a simple quote. ------- xt/single_quotes.t doesn't catch it because the test only searches in koha-tmpl/opac-tmpl/bootstrap/en/ koha-tmpl/intranet-tmpl/prog/en/