diff --git a/radicale/group/from_auth.py b/radicale/group/from_auth.py
new file mode 100644
index 00000000..b0372d85
--- /dev/null
+++ b/radicale/group/from_auth.py
@@ -0,0 +1,35 @@
+# This file is part of Radicale - CalDAV and CardDAV server
+# Copyright © 2026-2026 Peter Bieringer <pb@bieringer.de>
+#
+# This library is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Radicale.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+A dummy backend that returns no group but check whether authentication type supports it.
+
+"""
+from typing import Set
+
+from radicale import config, group
+
+
+class Group(group.BaseGroup):
+
+    def __init__(self, configuration: config.Configuration) -> None:
+        super().__init__(configuration)
+        auth_type = configuration.get("auth", "type")
+        if auth_type not in ["ldap", "pam"]:
+            raise RuntimeError("group-type 'auth_type' is not supported by auth/type %r" % auth_type)
+
+    def _groups(self, login: str) -> Set[str]:
+        return set([])