diff --git a/product/CMFActivity/Activity/SQLDict.py b/product/CMFActivity/Activity/SQLDict.py
index dc8e1351770c62cb99a93c89b2e65b87e8522595..e67a1cdb8b99cfec90bd36eaa1e453cbc467f3ed 100644
--- a/product/CMFActivity/Activity/SQLDict.py
+++ b/product/CMFActivity/Activity/SQLDict.py
@@ -313,7 +313,7 @@ class SQLDict(RAMDict):
           # Unfortunately, database adapters may raise an exception against abort.
           LOG('SQLDict', WARNING, 'abort failed, thus some objects may be modified accidentally')
           pass
-        if issubclass(exc, ConflictError):
+        if isinstance(exc, ConflictError):
           # For a conflict error, simply delay the operations.
           for uid_list in uid_list_list:
             if len(uid_list):
diff --git a/product/CMFActivity/Activity/SQLQueue.py b/product/CMFActivity/Activity/SQLQueue.py
index 6bbe52a175d28fb02c8f0d8e6af44d0720580edb..aabd9c0b4515486c1172bedaaf4b684694fdc3c3 100644
--- a/product/CMFActivity/Activity/SQLQueue.py
+++ b/product/CMFActivity/Activity/SQLQueue.py
@@ -134,7 +134,7 @@ class SQLQueue(RAMQueue):
           LOG('SQLQueue', WARNING, 'abort failed, thus some objects may be modified accidentally')
           pass
 
-        if issubclass(exc, ConflictError):
+        if isinstance(exc, ConflictError):
           # If a conflict occurs, delay the operation.
           activity_tool.SQLQueue_setPriority(uid = line.uid, date = next_processing_date,
                                              priority = line.priority)