Frontend Form for editing entries HTTP Exception

Question

I took the example form of the craft CMS Entry Form Documentation page and tried to use it on a test site. However i always get a HttpException after submitting the Frontend Form.

Here's the Stack Trace.

And a Screenshot of the Error page

Here's the code

<form method="post" accept-charset="UTF-8">
  {{ csrfInput() }}
  {{ actionInput('entries/save-entry') }}
  {{ redirectInput('viewentry/{slug}') }}
  {{ hiddenInput('sectionId', entry.sectionId) }}
  {{ hiddenInput('enabled', '1') }}
  {{ hiddenInput('entryId', entry.id) }}

  <label for="title">Title</label>
  <input id="title" type="text" name="title"
      {%- if entry is defined %} value="{{ entry.title }}"{% endif -%}>

  {% if entry is defined %}
      {{ _self.errorList(entry.getErrors('title')) }}
  {% endif %}

  <input type="submit" value="Publish">
</form>

It's a multi-site with 3 languages. So maybe its related to the languages. But i couldn't find any informations for a frontend form in multi-sites.