diff --git a/src/core/models/assemblies.py b/src/core/models/assemblies.py
index eee23e2b6fbf96d7febbf1f57b919cb6eb702dec..5627235495a173fd6478caeb685d7fc533f43f89 100644
--- a/src/core/models/assemblies.py
+++ b/src/core/models/assemblies.py
@@ -37,17 +37,21 @@ from core.validators import FileSizeValidator, ImageDimensionValidator
 
 @rules.predicate
 def is_assembly_member(user: PlatformUser, assembly: 'Assembly') -> bool:
+    if assembly is None:
+        return False
     return assembly.has_user(user)
 
 
 @rules.predicate
 def is_assembly_manager(user: PlatformUser, assembly: 'Assembly') -> bool:
+    if assembly is None:
+        return False
     return assembly.user_can_manage(user)
 
 
 @rules.predicate
 def is_habitat_manager(user: PlatformUser, assembly: 'Assembly') -> bool:
-    if assembly.parent is None:
+    if assembly is None or assembly.parent is None:
         return False
     return assembly.parent.user_can_manage(user)