diff --git a/capsul/attributes/completion_engine.py b/capsul/attributes/completion_engine.py
index 5a319ad7..8ca094c9 100644
--- a/capsul/attributes/completion_engine.py
+++ b/capsul/attributes/completion_engine.py
@@ -987,11 +987,11 @@ def get_completion_engine(self, process, name=None):
         instance, which is quite incomplete.
         '''
         if hasattr(process, 'completion_engine'):
+            ce = process.completion_engine
             # just in case the process has been changed in the CE
-            if process.completion_engine.process != process:
-                process.completion_engine.process = weak_proxy(
-                    process, process.completion_engine._clear_node)
-            return process.completion_engine
+            if ce and ce.process != process:
+                ce.process = weak_proxy(process, ce._clear_node)
+            return ce
 
         if isinstance(process, Switch):
             return SwitchCompletionEngine(process, name=name)
diff --git a/capsul/attributes/completion_engine_factory.py b/capsul/attributes/completion_engine_factory.py
index 1929973d..92d891b3 100644
--- a/capsul/attributes/completion_engine_factory.py
+++ b/capsul/attributes/completion_engine_factory.py
@@ -38,11 +38,11 @@ def get_completion_engine(self, process, name=None):
         conform to the API.
         '''
         if hasattr(process, 'completion_engine'):
+            ce = process.completion_engine
             # just in case the process has been changed in the CE
-            if process.completion_engine.process != process:
-                process.completion_engine.process = weak_proxy(
-                    process, process.completion_engine._clear_node)
-            return process.completion_engine
+            if ce and ce.process != process:
+                ce.process = weak_proxy(process, ce._clear_node)
+            return ce
 
         study_config = process.get_study_config()