diff --git a/src/mcts.jl b/src/mcts.jl
index 6f68fa1..28810e4 100644
--- a/src/mcts.jl
+++ b/src/mcts.jl
@@ -177,9 +177,14 @@ function simulate(a, node::MCTSNode, decisionMaker::Function, progressValueEstim
     if node.isterminal
       break
     else
-      simTrajectoryReward += node.reward
-      expand(a, node, decisionMaker, progressValueEstimator, isterminal, n=n)
-      node = selectChildNode(node)
+      try
+        simTrajectoryReward += node.reward
+        expand(a, node, decisionMaker, progressValueEstimator, isterminal, n=n)
+        node = selectChildNode(node)
+      catch
+        # if error occurs, break and try again later
+        break
+      end
     end
   end