diff --git a/game-app/game-core/src/main/java/games/strategy/engine/framework/HistorySynchronizer.java b/game-app/game-core/src/main/java/games/strategy/engine/framework/HistorySynchronizer.java
index b4d722c08a0..d9c3197af0f 100644
--- a/game-app/game-core/src/main/java/games/strategy/engine/framework/HistorySynchronizer.java
+++ b/game-app/game-core/src/main/java/games/strategy/engine/framework/HistorySynchronizer.java
@@ -46,7 +46,7 @@ public void startHistoryEvent(final String event, final Object renderingData) {
                   } catch (ConcurrentModificationException e) {
                     // Instrumented to diagnose what exactly is causing this.
                     throw new ConcurrentModificationException(
-                        "Failed to map renderingData=" + renderingData + " for event=" + event);
+                        "Failed to map renderingData=" + renderingData + " for event=" + event, e);
                   }
                 });
           }