diff --git a/force_bdss/core_plugins/csv_extractor/csv_extractor/csv_extractor_bundle.py b/force_bdss/core_plugins/csv_extractor/csv_extractor/csv_extractor_bundle.py
index b905c73e205a29b5e1da2dd2f70f951444c8fec7..b0a2e474c9bd49ca1aa6b224c555dfd9e742c703 100644
--- a/force_bdss/core_plugins/csv_extractor/csv_extractor/csv_extractor_bundle.py
+++ b/force_bdss/core_plugins/csv_extractor/csv_extractor/csv_extractor_bundle.py
@@ -11,8 +11,11 @@ from .csv_extractor_data_source import CSVExtractorDataSource
 class CSVExtractorBundle(HasStrictTraits):
     name = String("csv_extractor")
 
-    def create_model(self, model_data):
-        return CSVExtractorModel.from_json(model_data)
+    def create_model(self, model_data=None):
+        if model_data is None:
+            return CSVExtractorModel()
+        else:
+            return CSVExtractorModel.from_json(model_data)
 
     def create_data_source(self, application, model):
         return CSVExtractorDataSource(self, application, model)
diff --git a/force_bdss/core_plugins/test_kpi/kpi_adder/kpi_adder_bundle.py b/force_bdss/core_plugins/test_kpi/kpi_adder/kpi_adder_bundle.py
index d3fef6f3b8d3ab4ac4bd4e982d7d78bb476608c4..336cb374008c189534801ee93f9b74ede066abd4 100644
--- a/force_bdss/core_plugins/test_kpi/kpi_adder/kpi_adder_bundle.py
+++ b/force_bdss/core_plugins/test_kpi/kpi_adder/kpi_adder_bundle.py
@@ -11,8 +11,11 @@ from .kpi_adder_calculator import KPIAdderCalculator
 class KPIAdderBundle(HasStrictTraits):
     name = String("kpi_adder")
 
-    def create_model(self, model_data):
-        return KPIAdderModel.from_json(model_data)
+    def create_model(self, model_data=None):
+        if model_data is None:
+            return KPIAdderModel()
+        else:
+            return KPIAdderModel.from_json(model_data)
 
     def create_data_source(self, application, model):
         return KPIAdderCalculator(self, application, model)
diff --git a/force_bdss/core_plugins/test_mco/dakota/dakota_bundle.py b/force_bdss/core_plugins/test_mco/dakota/dakota_bundle.py
index effed5735912edbfbd331e04a69aaf1dfce4b59e..3d534742f15abd2686f68a5752ec09cf9afcc725 100644
--- a/force_bdss/core_plugins/test_mco/dakota/dakota_bundle.py
+++ b/force_bdss/core_plugins/test_mco/dakota/dakota_bundle.py
@@ -14,8 +14,11 @@ from .dakota_optimizer import DakotaOptimizer
 class DakotaBundle(HasStrictTraits):
     name = String("dakota")
 
-    def create_model(self, model_data):
-        return DakotaModel.from_json(model_data)
+    def create_model(self, model_data=None):
+        if model_data is None:
+            return DakotaModel()
+        else:
+            return DakotaModel.from_json(model_data)
 
     def create_optimizer(self, application, model):
         return DakotaOptimizer(self, application, model)
diff --git a/force_bdss/data_sources/i_data_source_bundle.py b/force_bdss/data_sources/i_data_source_bundle.py
index d7f80ac2ccf50d8703c95aeeda8fc6f00385f26b..5db54c836efe5da59391eb4db5711f7dad973913 100644
--- a/force_bdss/data_sources/i_data_source_bundle.py
+++ b/force_bdss/data_sources/i_data_source_bundle.py
@@ -7,5 +7,5 @@ class IDataSourceBundle(Interface):
     def create_data_source(self, application, model):
         pass
 
-    def create_model(self, model_data):
+    def create_model(self, model_data=None):
         pass
diff --git a/force_bdss/kpi/i_kpi_calculator_bundle.py b/force_bdss/kpi/i_kpi_calculator_bundle.py
index 6a37749121e93af5e1937943438582b95a60c123..42f780e5efff2c7f7908d79dc149894215bc143c 100644
--- a/force_bdss/kpi/i_kpi_calculator_bundle.py
+++ b/force_bdss/kpi/i_kpi_calculator_bundle.py
@@ -7,5 +7,5 @@ class IKPICalculatorBundle(Interface):
     def create_kpi_calculator(self, application, model):
         pass
 
-    def create_model(self, model_data):
+    def create_model(self, model_data=None):
         pass
diff --git a/force_bdss/mco/i_multi_criteria_optimizer_bundle.py b/force_bdss/mco/i_multi_criteria_optimizer_bundle.py
index f84cca5379b0bacb7ca11365ac84777307015cdb..69fe7a79a139ffbb48f71f0cd7f99d4cec8813ac 100644
--- a/force_bdss/mco/i_multi_criteria_optimizer_bundle.py
+++ b/force_bdss/mco/i_multi_criteria_optimizer_bundle.py
@@ -7,7 +7,7 @@ class IMultiCriteriaOptimizerBundle(Interface):
     def create_optimizer(self, application, model):
         pass
 
-    def create_model(self, model_data):
+    def create_model(self, model_data=None):
         pass
 
     def create_communicator(self, model_data):