--- ../src-base/minecraft/net/minecraft/server/management/UserListOps.java
+++ ../src-work/minecraft/net/minecraft/server/management/UserListOps.java
@@ -35,6 +35,7 @@
 
     protected String func_152699_b(GameProfile p_152699_1_)
     {
+        if (p_152699_1_ == null || p_152699_1_.getId() == null) return "invalid"; // Cauldron - handle GameProfiles with no ID
         return p_152699_1_.getId().toString();
     }