diff --git a/neutron_lib/exceptions/address_scope.py b/neutron_lib/exceptions/address_scope.py
index ecc2a621e..c4d27e7c4 100644
--- a/neutron_lib/exceptions/address_scope.py
+++ b/neutron_lib/exceptions/address_scope.py
@@ -29,3 +29,8 @@ class AddressScopeInUse(exceptions.InUse):
 class AddressScopeUpdateError(exceptions.BadRequest):
     message = _("Unable to update address scope %(address_scope_id)s : "
                 "%(reason)s.")
+
+
+class NetworkAddressScopeAffinityError(exceptions.BadRequest):
+    message = _("Subnets of the same address family hosted on the same "
+                "network must all participate in the same address scope.")
diff --git a/releasenotes/notes/add-network-address-scope-affinity-error-8f6b4493a92142d4.yaml b/releasenotes/notes/add-network-address-scope-affinity-error-8f6b4493a92142d4.yaml
new file mode 100644
index 000000000..e04e8d268
--- /dev/null
+++ b/releasenotes/notes/add-network-address-scope-affinity-error-8f6b4493a92142d4.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    A new exception named ``NetworkAddressScopeAffinityError`` has been added
+    in neutron_lib/exceptions/address_scope.py. This is to be raised by
+    consumers when network / address scope affinity constraints are violated
+    on subnet creation and subnet pool updates.