diff --git a/xmodule/mongo_utils.py b/xmodule/mongo_utils.py
index b86abd28b466..5aecbfc405df 100644
--- a/xmodule/mongo_utils.py
+++ b/xmodule/mongo_utils.py
@@ -30,8 +30,11 @@ def connect_to_mongodb(
     handles AutoReconnect errors by retrying read operations, since these exceptions
     typically indicate a temporary step-down condition for MongoDB.
     """
-    # If the MongoDB server uses a separate authentication database that should be specified here
-    auth_source = kwargs.get('authsource', '') or None
+    # If the MongoDB server uses a separate authentication database that should be specified here.
+    # Convert the lowercased authsource parameter to the camel-cased authSource expected by MongoClient.
+    auth_source = db
+    if auth_source_key := {'authSource', 'authsource'}.intersection(set(kwargs.keys())):
+        auth_source = kwargs.pop(auth_source_key.pop()) or db
 
     # sanitize a kwarg which may be present and is no longer expected
     # AED 2020-03-02 TODO: Remove this when 'auth_source' will no longer exist in kwargs
@@ -63,7 +66,7 @@ def connect_to_mongodb(
     }
 
     if user is not None and password is not None and not db.startswith('test_'):
-        connection_params.update({'username': user, 'password': password, 'authSource': db})
+        connection_params.update({'username': user, 'password': password, 'authSource': auth_source})
 
     mongo_conn = pymongo.MongoClient(**connection_params)