diff --git a/airbyte-server/src/main/java/io/airbyte/server/handlers/ConnectionsHandler.java b/airbyte-server/src/main/java/io/airbyte/server/handlers/ConnectionsHandler.java
index 07722d15b8b7..c14b8874c69e 100644
--- a/airbyte-server/src/main/java/io/airbyte/server/handlers/ConnectionsHandler.java
+++ b/airbyte-server/src/main/java/io/airbyte/server/handlers/ConnectionsHandler.java
@@ -121,11 +121,17 @@ public ConnectionRead createConnection(final ConnectionCreate connectionCreate)
 
     final UUID connectionId = uuidGenerator.get();
 
+    // If not specified, default the NamespaceDefinition to 'source'
+    final NamespaceDefinitionType namespaceDefinitionType =
+        connectionCreate.getNamespaceDefinition() == null
+            ? NamespaceDefinitionType.SOURCE
+            : Enums.convertTo(connectionCreate.getNamespaceDefinition(), NamespaceDefinitionType.class);
+
     // persist sync
     final StandardSync standardSync = new StandardSync()
         .withConnectionId(connectionId)
         .withName(connectionCreate.getName() != null ? connectionCreate.getName() : defaultName)
-        .withNamespaceDefinition(Enums.convertTo(connectionCreate.getNamespaceDefinition(), NamespaceDefinitionType.class))
+        .withNamespaceDefinition(namespaceDefinitionType)
         .withNamespaceFormat(connectionCreate.getNamespaceFormat())
         .withPrefix(connectionCreate.getPrefix())
         .withSourceId(connectionCreate.getSourceId())