diff --git a/common/lib/xmodule/xmodule/vertical_block.py b/common/lib/xmodule/xmodule/vertical_block.py
index c5dff07c0d..52266d0e80 100644
--- a/common/lib/xmodule/xmodule/vertical_block.py
+++ b/common/lib/xmodule/xmodule/vertical_block.py
@@ -66,7 +66,9 @@ class VerticalBlock(SequenceFields, XModuleFields, StudioEditableBlock, XmlParse
                     usage_key=self.location),  # pylint: disable=no-member
             if 'username' not in child_context:
                 user_service = self.runtime.service(self, 'user')
-                child_context['username'] = user_service.get_current_user().opt_attrs['edx-platform.username']
+                child_context['username'] = user_service.get_current_user().opt_attrs.get(
+                    'edx-platform.username'
+                )
 
         child_blocks = self.get_display_items()