I have a elasticsearch backend (7.14.0) and wagtail (2.14.1) and I want to include a fulltext-search at the body field of my page. When search something in frontend, I get
SearchFieldError at /search/
Cannot search with field "body". Please add index.SearchField('body') to 
Page.search_fields.
Request Method: GET
Request URL:    https://my.site/search/?query=impres
Django Version: 3.2.4
Exception Type: SearchFieldError
Exception Value:    
Cannot search with field "body". Please add index.SearchField('body') to         
Page.search_fields.
Exception Location: /var/www/vhosts/my.site/dev4/venv/lib/python3.6/site-packages/wagtail/search/backends/base.py, line 163, in check
Python Executable:  /var/www/vhosts/my.site/dev4/venv/bin/python
Python Version: 3.6.9
Python Path:    
['/var/www/vhosts/my.site/dev4/venv/bin',
 '/var/www/vhosts/my.site/dev4/mysite/mysite',
 '/var/www/vhosts/my.site/dev4/mysite',
 '/var/www/vhosts/my.site/dev4',
 '/usr/share/passenger/helper-scripts',
 '/usr/lib/python36.zip',
 '/usr/lib/python3.6',
 '/usr/lib/python3.6/lib-dynload',
 '/var/www/vhosts/my.site/dev4/venv/lib/python3.6/site-packages']
Server time:    Mon, 23 Aug 2021 05:24:18 +0000
my views.py:
from django.core.paginator import EmptyPage, PageNotAnInteger, Paginator
from django.template.response import TemplateResponse
from wagtail.core.models import Page
from wagtail.search.models import Query
def search(request):
    search_query = request.GET.get('query', None)
    page = request.GET.get('page', 1)
    # Search
    if search_query:
        #search_results = Page.objects.live().search(search_query)
        # exclude some search results
        search_results = Page.objects.live()\
        .exclude(title='Sie sind nun ausgeloggt.')\
        .exclude(title='Sie sind nun eingeloggt.')\
        .exclude(title='Passwort erfolgreich geändert.')\
        .search(search_query, fields=["title", "body"])
        query = Query.get(search_query)
        # Record hit
        query.add_hit()
    else:
        search_results = Page.objects.none()
    # Pagination
    paginator = Paginator(search_results, 10)
    try:
        search_results = paginator.page(page)
    except PageNotAnInteger:
        search_results = paginator.page(1)
    except EmptyPage:
        search_results = paginator.page(paginator.num_pages)
    return TemplateResponse(request, 'search/search.html', {
        'search_query': search_query,
        'search_results': search_results,
    })
my models.py:
from django.db import models
from wagtail.core.models import Page
from wagtail.core.fields import RichTextField
from wagtail.admin.edit_handlers import FieldPanel
from wagtail.search import index
class HomePage(Page):
    body = RichTextField(blank=True)
    content_panels = Page.content_panels + [
        FieldPanel('body', classname="full"),
    ]
    # Search index configuration
    search_fields = Page.search_fields + [ # Inherit search_fields from Page
        index.SearchField('body'),
    ]
So I already added index.SearchField('body') to Page.search_fields and can't find any type-o's. Any idea what I'm doing wrong?