diff --git a/src/python_be.cc b/src/python_be.cc
index 33b2ec77..1f5a2e34 100644
--- a/src/python_be.cc
+++ b/src/python_be.cc
@@ -2005,6 +2005,29 @@ ModelState::ValidateModelConfig()
   return nullptr;
 }
 
+TRITONSERVER_Error*
+ModelState::SetModelConfig()
+{
+  BackendModel::SetModelConfig();
+  // `Update model_transaction_policy` if setting was set
+  // with `set_model_transaction_policy`
+  triton::common::TritonJson::Value model_transaction_policy;
+  bool is_decoupled = false;
+  if (ModelConfig().Find(
+          "model_transaction_policy", &model_transaction_policy)) {
+    triton::common::TritonJson::Value decoupled;
+    if (model_transaction_policy.Find("decoupled", &decoupled)) {
+      auto error = decoupled.AsBool(&is_decoupled);
+      if (error != nullptr) {
+        throw BackendModelException(error);
+      }
+      SetDecoupled(is_decoupled);
+    }
+  }
+
+  return nullptr;
+}
+
 
 extern "C" {
 
diff --git a/src/python_be.h b/src/python_be.h
index fce1f417..f8ec8cfa 100644
--- a/src/python_be.h
+++ b/src/python_be.h
@@ -238,6 +238,9 @@ class ModelState : public BackendModel {
   // Is decoupled API being used.
   bool IsDecoupled() { return decoupled_; }
 
+  // Set decoupled mode
+  void SetDecoupled(bool decoupled) { decoupled_ = decoupled; }
+
   // Returns the value in the `runtime_modeldir_` field
   std::string RuntimeModelDir() { return runtime_modeldir_; }
 
@@ -247,6 +250,10 @@ class ModelState : public BackendModel {
   // Validate Model Configuration
   TRITONSERVER_Error* ValidateModelConfig();
 
+  // Overrides `BackendModel::SetModelConfig` to also
+  // set `ModelState::decoupled_`
+  TRITONSERVER_Error* SetModelConfig();
+
   // Auto-complete stub
   std::unique_ptr<StubLauncher>& Stub() { return auto_complete_stub_; }
 
diff --git a/src/resources/triton_python_backend_utils.py b/src/resources/triton_python_backend_utils.py
index 9828ab5b..b4732da6 100644
--- a/src/resources/triton_python_backend_utils.py
+++ b/src/resources/triton_python_backend_utils.py
@@ -394,7 +394,7 @@ def add_input(self, input):
                     + input["name"]
                     + "' in auto-complete-config function for model '"
                     + self._model_config["name"]
-                    + "' contains property other than 'name', 'data_type' and 'dims'."
+                    + "' contains property other than 'name', 'data_type', 'dims' and 'optional'."
                 )
 
         if "name" not in input: