DoesNotExist at /admin/blog/blog/add/: blog matching query does not exist

[mailinglists at vanwingerde.nl]

Suddenly I can no longer add blogs to Django. Django says 'blog
matching query does not exist'. That seems strange to me because I want
to add something to the database and not request a blog. What could be
going on here?

admin.py:
class blogadmin(admin.ModelAdmin):
    def save_model(self, request, obj, form, change):
        if not change:
            obj.added_by_user = request.user.username
            obj.ip_added = request.META['REMOTE_ADDR']
            if obj.ip_added == '127.0.0.1':
                obj.ip_added = request.META['HTTP_X_FORWARDED_FOR']
            obj.publish = False
            del obj.publish_date
        else:
            obj.changed_by_user = request.user.username
            obj.ip_changed = request.META['REMOTE_ADDR']
            if obj.ip_changed == '127.0.0.1':
                obj.ip_changed = request.META['HTTP_X_FORWARDED_FOR']
            if obj.publish == True:
                if not obj.publish_date:
                    obj.publish_date = obj.datetime_changed
        super(blogadmin,self).save_model(request, obj, form, change)

I can add text, photographs etc., but no blogs.

Notifications:
DoesNotExist at /admin/blog/blog/add/

blog matching query does not exist.

Request Method: 	POST
Request URL: 	http://127.0.0.1:8001/admin/blog/blog/add/
Django Version: 	4.1.1
Exception Type: 	DoesNotExist
Exception Value: 	

blog matching query does not exist.

Traceback
Environment:
Request Method: POST
Request URL: http://127.0.0.1:8001/admin/blog/blog/add/

Django Version: 4.1.1
Python Version: 3.10.5
Installed Applications:
['grappelli',
 'django.contrib.admin',
 'django.contrib.admindocs',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'blog.apps.BlogConfig']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.contrib.admindocs.middleware.XViewMiddleware']

Traceback (most recent call last):
  File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/core/handlers/exception.py",
line 55, in inner response = get_response(request) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/core/handlers/base.py",
line 197, in _get_response response = wrapped_callback(request,
*callback_args, **callback_kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/contrib/admin/options.py",
line 686, in wrapper return self.admin_site.admin_view(view)(*args,
**kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/utils/decorators.py",
line 133, in _wrapped_view response = view_func(request, *args,
**kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/views/decorators/cache.py",
line 62, in _wrapped_view_func response = view_func(request, *args,
**kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/contrib/admin/sites.py",
line 242, in inner return view(request, *args, **kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/contrib/admin/options.py",
line 1890, in add_view return self.changeform_view(request, None,
form_url, extra_context) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/utils/decorators.py",
line 46, in _wrapper return bound_method(*args, **kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/utils/decorators.py",
line 133, in _wrapped_view response = view_func(request, *args,
**kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/contrib/admin/options.py",
line 1750, in changeform_view return self._changeform_view(request,
object_id, form_url, extra_context) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/contrib/admin/options.py",
line 1802, in _changeform_view self.save_model(request, new_object,
form, not add) File "/var/django/liakoster.nl/blog-1/blog/admin.py",
line 26, in save_model super(blogadmin,self).save_model(request, obj,
form, change) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/contrib/admin/options.py",
line 1225, in save_model obj.save() File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/base.py",
line 831, in save self.save_base( File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/base.py",
line 882, in save_base updated = self._save_table( File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/base.py",
line 1025, in _save_table results = self._do_insert( File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/base.py",
line 1066, in _do_insert return manager._insert( File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/manager.py",
line 85, in manager_method return getattr(self.get_queryset(),
name)(*args, **kwargs) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/query.py",
line 1790, in _insert return
query.get_compiler(using=using).execute_sql(returning_fields) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/sql/compiler.py",
line 1656, in execute_sql for sql, params in self.as_sql(): File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/sql/compiler.py",
line 1580, in as_sql value_rows = [ File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/sql/compiler.py",
line 1581, in <listcomp> [ File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/sql/compiler.py",
line 1582, in <listcomp> self.prepare_value(field,
self.pre_save_val(field, obj)) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/sql/compiler.py",
line 1530, in pre_save_val return field.pre_save(obj, add=True) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/fields/__init__.py",
line 1548, in pre_save return super().pre_save(model_instance, add)
File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/fields/__init__.py",
line 1411, in pre_save return super().pre_save(model_instance, add)
File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/fields/__init__.py",
line 905, in pre_save return getattr(model_instance, self.attname) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/query_utils.py",
line 178, in __get__ instance.refresh_from_db(fields=[field_name]) File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/base.py",
line 741, in refresh_from_db db_instance = db_instance_qs.get() File
"/var/django/liakoster.nl/blog-1/lib/python3.10/site-packages/django/db/models/query.py",
line 650, in get raise self.model.DoesNotExist(

Exception Type: DoesNotExist at /admin/blog/blog/add/
Exception Value: blog matching query does not exist.
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