diff --git a/lib/shared/message-utils.js b/lib/shared/message-utils.js
--- a/lib/shared/message-utils.js
+++ b/lib/shared/message-utils.js
@@ -115,12 +115,9 @@
   threadInfos: { +[id: string]: ThreadInfo },
 ): ?MessageInfo {
   const creatorInfo = userInfos[rawMessageInfo.creatorID];
-  if (!creatorInfo) {
-    return null;
-  }
   const creator = {
     id: rawMessageInfo.creatorID,
-    username: creatorInfo.username,
+    username: creatorInfo ? creatorInfo.username : 'anonymous',
     isViewer: rawMessageInfo.creatorID === viewerID,
   };