<form id="language-switcher" class="languages go" method="get" action="">
  <label for="language">{{ _('Other languages:') }}</label>
  <select id="language" name="lang" dir="ltr">
    {% for code, name in LANGUAGES|dictsort -%}
      <option value="{{ code }}" {{ code|ifeq(LANG|lower, "selected") }}>
        {{ name }}
      </option>
    {%- endfor %}
  </select>
  <button class="js-hide" type="submit">{{ _('Go') }}</button>
</form>

<form id="language-switcher" class="languages go" method="GET">
  <label for="language">{{ _('Other languages:') }}</label>
  <select id="language" name="lang" dir="ltr">
    {% for code, name in LANGUAGES|dictsort -%}
      <option value="{{ code }}" {{ code|ifeq(LANG|lower, "selected") }}>
        {{ name }}
      </option>
    {%- endfor %}
  </select>
  <button class="js-hide" type="submit">{{ _('Go') }}</button>
</form>

Remove action attribute from language switcher
Remove action attribute from language switcher

Empty action attribute causes a validation error, and omitting
it works just as well.
