diff --git a/users/models/inbox_message.py b/users/models/inbox_message.py
index 155484a..d8b6e61 100644
--- a/users/models/inbox_message.py
+++ b/users/models/inbox_message.py
@@ -154,7 +154,7 @@ class InboxMessageStates(StateGraph):
                                 f"Cannot handle activity of type __internal__.{unknown}"
                             )
                 case unknown:
-                    raise ValueError(f"Cannot handle activity of type {unknown}")
+                    return cls.errored
             return cls.processed
         except (ActivityPubError, JsonLdError):
             return cls.errored