diff --git a/internal/api/environments.go b/internal/api/environments.go
index ce834384..dee41a9b 100644
--- a/internal/api/environments.go
+++ b/internal/api/environments.go
@@ -128,6 +128,7 @@ func (e *EnvironmentController) createOrUpdate(writer http.ResponseWriter, reque
 	})
 	if err != nil {
 		writeInternalServerError(request.Context(), writer, err, dto.ErrorUnknown)
+		return
 	}
 
 	if created {
diff --git a/internal/environment/abstract_manager.go b/internal/environment/abstract_manager.go
index ee2687f1..4d58dcfa 100644
--- a/internal/environment/abstract_manager.go
+++ b/internal/environment/abstract_manager.go
@@ -49,7 +49,7 @@ func (n *AbstractManager) Get(_ context.Context, _ dto.EnvironmentID, _ bool) (r
 func (n *AbstractManager) CreateOrUpdate(_ context.Context, _ dto.EnvironmentID, _ dto.ExecutionEnvironmentRequest) (
 	bool, error,
 ) {
-	return false, nil
+	return false, dto.ErrNotSupported
 }
 
 func (n *AbstractManager) Delete(environmentID dto.EnvironmentID) (bool, error) {