diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
index c82796b381..4baf12caaf 100644
--- a/.github/workflows/pytest.yml
+++ b/.github/workflows/pytest.yml
@@ -120,6 +120,24 @@ jobs:
       - run: python -Im pip install -e .[dev]
       - run: python -Ic 'import rdmo; print(rdmo.__version__)'
 
+  optional-dependencies:
+    name: Test installation of optional-dependencies
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: "3.11"
+          cache: pip
+      - name: Install os requirements for python-ldap
+        run: |
+          sudo apt update
+          sudo apt install --yes libldap2-dev libsasl2-dev
+      - run: python -m pip install --upgrade pip setuptools
+      - run: python -m pip install .[allauth,ci,dev,gunicorn,ldap,memcached,mysql,postgres,pytest]
+      - run: python -m pip freeze
+      - run: python -m pip list --outdated
+
   required-checks-pass:
     if: always()
     needs:
@@ -127,6 +145,7 @@ jobs:
       - test
       - coveralls
       - dev-setup
+      - optional-dependencies
     runs-on: ubuntu-22.04
     steps:
       - uses: re-actors/alls-green@release/v1
diff --git a/pyproject.toml b/pyproject.toml
index b93e051421..8f9fc846ec 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,13 +15,13 @@ keywords = [
 ]
 license = {text = "Apache-2.0"}
 authors = [
-    {name = "RDMO Arbeitsgemeinschaft", email = "rdmo-team@listserv.dfn.de"},
+  {name = "RDMO Arbeitsgemeinschaft", email = "rdmo-team@listserv.dfn.de"},
 ]
 requires-python = ">=3.8"
 classifiers = [
   "Development Status :: 5 - Production/Stable",
   "Environment :: Web Environment",
-  "Framework :: Django :: 3.2",
+  "Framework :: Django :: 4.2",
   "Intended Audience :: Science/Research",
   "License :: OSI Approved :: Apache Software License",
   "Operating System :: OS Independent",
@@ -37,60 +37,66 @@ dynamic = [
   "version",
 ]
 dependencies = [
-  "defusedcsv~=2.0.0",
-  "defusedxml~=0.7.1",
-  "Django~=3.2.20",
-  "django-allauth~=0.53.1",
-  "django-cleanup~=6.0.0",
+  "defusedcsv~=2.0",
+  "defusedxml~=0.7",
+  "django~=4.2",
+  "django-cleanup~=8.0",
   "django-compressor~=4.4",
-  "django-extensions~=3.2.0",
-  "django-filter~=21.1",
-  "django-libsass==0.9",
-  "django-mathfilters~=1.0.0",
-  "django-mptt~=0.13.4",
-  "django-rest-swagger~=2.2.0",
-  "django-settings-export~=1.2.1",
-  "django-widget-tweaks~=1.4.8",
-  "djangorestframework~=3.12.4",
-  "drf-extensions~=0.7.0",
-  "iso8601~=2.0.0",
-  "Markdown~=3.3.7",
-  "pypandoc~=1.10.0",
-  "rules~=3.3.0",
+  "django-extensions~=3.2",
+  "django-filter~=23.2",
+  "django-libsass~=0.9",
+  "django-mathfilters~=1.0",
+  "django-mptt~=0.14",
+  "django-rest-swagger~=2.2",
+  "django-settings-export~=1.2",
+  "django-widget-tweaks~=1.5",
+  "djangorestframework~=3.14",
+  "drf-extensions~=0.7",
+  "iso8601~=2.0",
+  "markdown~=3.4",
+  "pypandoc~=1.11",
+  "rules~=3.3",
 ]
 
 [project.optional-dependencies]
+allauth = [
+  "django-allauth~=0.56",
+]
 ci = [
-  "coveralls",
+  "coveralls~=3.3",
   "rdmo[dev]",
 ]
 dev = [
-  "django-debug-toolbar",
-  "pre-commit",
+  "django-debug-toolbar~=4.2",
+  "pre-commit~=3.4",
+  "rdmo[allauth]",
   "rdmo[pytest]",
 ]
 gunicorn = [
-  "gunicorn>=19.9",
+  "gunicorn~=21.2",
 ]
 ldap = [
-  "django-auth-ldap>=2",
+  "django-auth-ldap~=4.5",
 ]
 memcached = [
-  "python-memcached>=1.58",
+  "python-memcached~=1.5",
 ]
 mysql = [
-  "mysqlclient~=2.2.0",
+  "mysqlclient~=2.2",
 ]
 postgres = [
-  "psycopg2-binary~=2.9.6",
+  # once python 3.12 is officially released, the psycopg team will release a psycopg-binary for it.
+  # replace these two lines with "psycopg[binary]~=3.1"
+  "psycopg[binary]~=3.1; python_version<'3.12'",
+  "psycopg2-binary~=2.9; python_version>='3.12'",
 ]
 pytest = [
-  "pytest~=7.4.0",
-  "pytest-cov~=4.0.0",
-  "pytest-django~=4.5.0",
-  "pytest-mock~=3.11.0",
-  "pytest-randomly~=3.15.0",
-  "pytest-xdist~=3.3.1",
+  "pytest~=7.4",
+  "pytest-cov~=4.1",
+  "pytest-django~=4.5",
+  "pytest-mock~=3.11",
+  "pytest-randomly~=3.15",
+  "pytest-xdist~=3.3",
 ]
 
 [project.urls]
@@ -181,6 +187,18 @@ testpaths = ["rdmo"]
 python_files = "test_*[!.txt].py"
 pythonpath = [".", "testing"]
 addopts = "-p no:randomly"
+filterwarnings = [
+  # fail on RemovedInDjango50Warning exception
+  "error::django.utils.deprecation.RemovedInDjango50Warning",
+
+  # ignore warnings raised from within coreapi 2.3.3
+  "ignore:'cgi' is deprecated and slated for removal in Python 3.13:DeprecationWarning",
+  "ignore:pkg_resources is deprecated as an API:DeprecationWarning",
+
+  # ignore warnings raised from within django itself
+  # django/core/files/storage/__init__.py
+  "ignore:django.core.files.storage.get_storage_class is deprecated:django.utils.deprecation.RemovedInDjango51Warning",
+]
 
 [tool.coverage.run]
 source = ["rdmo"]
diff --git a/rdmo/accounts/forms.py b/rdmo/accounts/forms.py
index e8e5f3df61..e82f7f4c38 100644
--- a/rdmo/accounts/forms.py
+++ b/rdmo/accounts/forms.py
@@ -28,7 +28,6 @@ def __init__(self, *args, **kwargs):
         self.fields['last_name'].widget = forms.TextInput(attrs={'placeholder': _('Last name')})
 
         self.additional_fields = AdditionalField.objects.all()
-        self.additional_values = self.instance.additional_values.all()
 
         # add fields and init values for the Profile model
         for additional_field in self.additional_fields:
@@ -46,8 +45,10 @@ def __init__(self, *args, **kwargs):
 
             self.fields[additional_field.key] = field
 
-        for additional_field_value in self.additional_values:
-            self.fields[additional_field.key].initial = additional_field_value.value
+        # existing user is going to be updated
+        if self.instance.pk is not None:
+            for additional_field_value in AdditionalFieldValue.objects.filter(user=self.instance):
+                self.fields[additional_field.key].initial = additional_field_value.value
 
     def save(self, *args, **kwargs):
         super().save(*args, **kwargs)
diff --git a/rdmo/conditions/migrations/0025_alter_condition_editors.py b/rdmo/conditions/migrations/0025_alter_condition_editors.py
new file mode 100644
index 0000000000..1eee5e7ede
--- /dev/null
+++ b/rdmo/conditions/migrations/0025_alter_condition_editors.py
@@ -0,0 +1,24 @@
+# Generated by Django 4.2.5 on 2023-09-07 07:27
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('sites', '0002_alter_domain_unique'),
+        ('conditions', '0024_uri_path'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='condition',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this condition (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+    ]
diff --git a/rdmo/core/settings.py b/rdmo/core/settings.py
index 411bac5a79..2a00454d85 100644
--- a/rdmo/core/settings.py
+++ b/rdmo/core/settings.py
@@ -133,8 +133,6 @@
 
 USE_I18N = True
 
-USE_L10N = True
-
 USE_TZ = True
 
 LOGIN_URL = '/account/login/'
diff --git a/rdmo/domain/migrations/0050_alter_attribute_editors.py b/rdmo/domain/migrations/0050_alter_attribute_editors.py
new file mode 100644
index 0000000000..b85d4b3a8b
--- /dev/null
+++ b/rdmo/domain/migrations/0050_alter_attribute_editors.py
@@ -0,0 +1,24 @@
+# Generated by Django 4.2.5 on 2023-09-07 07:27
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('sites', '0002_alter_domain_unique'),
+        ('domain', '0049_attribute_add_editors'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='attribute',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this attribute (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+    ]
diff --git a/rdmo/options/migrations/0032_alter_option_editors_alter_optionset_editors.py b/rdmo/options/migrations/0032_alter_option_editors_alter_optionset_editors.py
new file mode 100644
index 0000000000..c00678692b
--- /dev/null
+++ b/rdmo/options/migrations/0032_alter_option_editors_alter_optionset_editors.py
@@ -0,0 +1,35 @@
+# Generated by Django 4.2.5 on 2023-09-07 07:27
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('sites', '0002_alter_domain_unique'),
+        ('options', '0031_add_editors'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='option',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this option (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+        migrations.AlterField(
+            model_name='optionset',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this option set (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+    ]
diff --git a/rdmo/projects/forms.py b/rdmo/projects/forms.py
index a6e32f7195..4ac7d42ab2 100644
--- a/rdmo/projects/forms.py
+++ b/rdmo/projects/forms.py
@@ -266,10 +266,15 @@ def __init__(self, *args, **kwargs):
 
         # add fields for the integration options
         for field in self.provider.fields:
-            try:
-                initial = IntegrationOption.objects.get(integration=self.instance, key=field.get('key')).value
-            except IntegrationOption.DoesNotExist:
+            # new integration instance is going to be created
+            if self.instance.pk is None:
                 initial = None
+            # existing integration is going to be updated
+            else:
+                try:
+                    initial = IntegrationOption.objects.get(integration=self.instance, key=field.get('key')).value
+                except IntegrationOption.DoesNotExist:
+                    initial = None
 
             if field.get('placeholder'):
                 attrs = {'placeholder': field.get('placeholder')}
diff --git a/rdmo/projects/views/membership.py b/rdmo/projects/views/membership.py
index 8392ff2d18..54242b57e9 100644
--- a/rdmo/projects/views/membership.py
+++ b/rdmo/projects/views/membership.py
@@ -66,7 +66,7 @@ class MembershipDeleteView(ObjectPermissionMixin, RedirectViewMixin, DeleteView)
     def get_queryset(self):
         return Membership.objects.filter(project_id=self.kwargs.get('project_id'))
 
-    def delete(self, *args, **kwargs):
+    def form_valid(self, form):
         self.obj = self.get_object()
 
         if (self.request.user in self.obj.project.owners) or is_site_manager(self.request.user):
diff --git a/rdmo/questions/migrations/0091_alter_catalog_editors_alter_page_editors_and_more.py b/rdmo/questions/migrations/0091_alter_catalog_editors_alter_page_editors_and_more.py
new file mode 100644
index 0000000000..e10a402832
--- /dev/null
+++ b/rdmo/questions/migrations/0091_alter_catalog_editors_alter_page_editors_and_more.py
@@ -0,0 +1,68 @@
+# Generated by Django 4.2.5 on 2023-09-07 07:27
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('sites', '0002_alter_domain_unique'),
+        ('questions', '0090_add_editors'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='catalog',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this catalog (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+        migrations.AlterField(
+            model_name='page',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this page (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+        migrations.AlterField(
+            model_name='question',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this question (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+        migrations.AlterField(
+            model_name='questionset',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this questionset (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+        migrations.AlterField(
+            model_name='section',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this section (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+    ]
diff --git a/rdmo/tasks/migrations/0036_alter_task_editors.py b/rdmo/tasks/migrations/0036_alter_task_editors.py
new file mode 100644
index 0000000000..29f322a893
--- /dev/null
+++ b/rdmo/tasks/migrations/0036_alter_task_editors.py
@@ -0,0 +1,24 @@
+# Generated by Django 4.2.5 on 2023-09-07 07:27
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('sites', '0002_alter_domain_unique'),
+        ('tasks', '0035_uri_path'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='task',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this task (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+    ]
diff --git a/rdmo/views/migrations/0029_alter_view_editors.py b/rdmo/views/migrations/0029_alter_view_editors.py
new file mode 100644
index 0000000000..1e2acb01bb
--- /dev/null
+++ b/rdmo/views/migrations/0029_alter_view_editors.py
@@ -0,0 +1,24 @@
+# Generated by Django 4.2.5 on 2023-09-07 07:27
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('sites', '0002_alter_domain_unique'),
+        ('views', '0028_uri_path'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='view',
+            name='editors',
+            field=models.ManyToManyField(
+                blank=True,
+                help_text='The sites that can edit this view (in a multi site setup).',
+                related_name='%(class)s_editors',
+                to='sites.site',
+                verbose_name='Editors',
+            ),
+        ),
+    ]
diff --git a/testing/config/settings/base.py b/testing/config/settings/base.py
index b954ad435b..4ee136eb4a 100644
--- a/testing/config/settings/base.py
+++ b/testing/config/settings/base.py
@@ -2,7 +2,7 @@
 
 from django.utils.translation import gettext_lazy as _
 
-from . import INSTALLED_APPS
+from . import INSTALLED_APPS, MIDDLEWARE
 
 DEBUG = False
 TEMPLATE_DEBUG = False
@@ -29,6 +29,10 @@
     'allauth.account'
 ]
 
+MIDDLEWARE += [
+    'allauth.account.middleware.AccountMiddleware'
+]
+
 ACCOUNT = True
 ACCOUNT_SIGNUP = True
 SOCIALACCOUNT = False
diff --git a/testing/config/settings/mysql.py b/testing/config/settings/mysql.py
index 2abee3e7af..9009619412 100644
--- a/testing/config/settings/mysql.py
+++ b/testing/config/settings/mysql.py
@@ -8,7 +8,6 @@
         'TEST': {
             'CHARSET': 'utf8',
             'COLLATION': 'utf8_general_ci',
-            'SERIALIZE': False,
         },
         'OPTIONS': {
             'init_command': "SET GLOBAL sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));"
diff --git a/testing/config/settings/postgres.py b/testing/config/settings/postgres.py
index d74efcdabd..a3e61d847f 100644
--- a/testing/config/settings/postgres.py
+++ b/testing/config/settings/postgres.py
@@ -5,6 +5,5 @@
         'USER': 'postgres_user',
         'PASSWORD': 'postgres_password',
         'HOST': '127.0.0.1',
-        'TEST': {'SERIALIZE': False},
     }
 }
diff --git a/testing/config/settings/sqlite3.py b/testing/config/settings/sqlite3.py
index 9f0a0ba8cf..8441c57a23 100644
--- a/testing/config/settings/sqlite3.py
+++ b/testing/config/settings/sqlite3.py
@@ -2,6 +2,5 @@
     'default': {
         'ENGINE': 'django.db.backends.sqlite3',
         'NAME': 'db.sqlite3',
-        'TEST': {'SERIALIZE': False},
     }
 }