diff --git a/src/caosdb/common/models.py b/src/caosdb/common/models.py
index 31a442006b5de7b9d168c80cb10930c108760252..122fa1db0f88df6dcb014b4dcba206ca5c0f6efa 100644
--- a/src/caosdb/common/models.py
+++ b/src/caosdb/common/models.py
@@ -46,13 +46,16 @@ from caosdb.common.utils import uuid, xml2str
 from caosdb.configuration import get_config
 from caosdb.connection.connection import get_connection
 from caosdb.connection.encode import MultipartParam, multipart_encode
-from caosdb.exceptions import (AmbiguityException, AuthorizationException,
+from caosdb.exceptions import (AmbiguityException,
+                               AuthorizationException,
                                CaosDBException, ConnectionException,
-                               ConsistencyError,
+                               ConsistencyError, ContainerError,
                                EntityDoesNotExistError, EntityError,
-                               EntityHasNoDatatypeError, TransactionError,
-                               UniqueNamesError, UnqualifiedParentsError,
-                               UnqualifiedPropertiesError, URITooLongException)
+                               EntityHasNoDatatypeError,
+                               TransactionError, UniqueNamesError,
+                               UnqualifiedParentsError,
+                               UnqualifiedPropertiesError,
+                               URITooLongException)
 from lxml import etree
 
 from .datatype import is_reference
@@ -3700,7 +3703,7 @@ def _evaluate_and_add_error(parent_error, ent):
             if err.code is not None:
                 if int(err.code) == 101:  # ent doesn't exist
                     new_exc = EntityDoesNotExistError(entity=ent,
-                                                      error=err))
+                                                      error=err)
                 elif int(err.code) == 110:  # ent has no data type
                     new_exc=EntityHasNoDatatypeError(entity = ent,
                                                        error = err)
@@ -3727,7 +3730,7 @@ def _evaluate_and_add_error(parent_error, ent):
                     new_exc = EntityError(entity=ent, error=err)
             else:  # No error code causes a general EntityError, too
                 new_exc = EntityError(entity=ent, error=err)
-            parent_err.add_error(new_exc)
+            parent_error.add_error(new_exc)
         # Check for possible errors in parents and properties that
         # weren't detected up to here
         if not found114:
@@ -3735,28 +3738,29 @@ def _evaluate_and_add_error(parent_error, ent):
             for prop in ent.get_properties():
                 dummy_err = _evaluate_and_add_error(dummy_err, prop)
             if dummy_err.get_errors():
-                parent_err.add_error(dummy_err)
+                parent_error.add_error(dummy_err)
         if not found116:
             dummy_err = EntityError(entity=ent)
             for par in ent.get_parents():
                 dummy_err = _evaluate_and_add_error(dummy_err, par)
             if dummy_err.get_errors():
-                parent_err.add_error(dummy_err)
+                parent_error.add_error(dummy_err)
 
     elif isinstance(ent, Container):
-        for err in ent.get_errors():
-            cont_err = ContainerError(entity=ent, error=err)
-            for elt in ent:
-                cont_err = _evaluate_and_add_error(cont_err, elt)
-            parent_err.add_error(cont_err)
+        if ent.get_errors() is not None:
+            for err in ent.get_errors():
+                cont_err = ContainerError(entity=ent, error=err)
+                for elt in ent:
+                    cont_err = _evaluate_and_add_error(cont_err, elt)
+                    parent_error.add_error(cont_err)
         # Cover possibility that the container doesn't have an error
         # but still contains entities that do
-        if not ent.get_errors():
+        else:
             dummy_err = ContainerError(entity=ent)
             for elt in ent:
                 dummy_err = _evaluate_and_add_error(dummy_err, elt)
             if dummy_err.get_errors():
-                parent_err.add_error(dummy_err)
+                parent_error.add_error(dummy_err)
 
     else:
         raise TypeError("Parameter ent is to be an Entity or a Container")