From eec9ef54b69d2a92a85333e251a85e4dcfa1e8c2 Mon Sep 17 00:00:00 2001
From: Roc13x <roc13x@gmail.com>
Date: Mon, 3 Aug 2020 23:57:53 +0100
Subject: [PATCH] Core/Instance: Prevent possible crash on boss minion despawn

---
 src/server/game/Instances/InstanceScript.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/server/game/Instances/InstanceScript.cpp b/src/server/game/Instances/InstanceScript.cpp
index 234b786964..3cd8506072 100644
--- a/src/server/game/Instances/InstanceScript.cpp
+++ b/src/server/game/Instances/InstanceScript.cpp
@@ -409,7 +409,8 @@ bool InstanceScript::SetBossState(uint32 id, EncounterState state)
                 if (GameObject* door = instance->GetGameObject(*i))
                     UpdateDoorState(door);
 
-        for (GuidSet::iterator i = bossInfo->minion.begin(); i != bossInfo->minion.end(); ++i)
+        GuidSet minions = bossInfo->minion; // Copy to prevent iterator invalidation (minion might be unsummoned in UpdateMinionState)
+        for (GuidSet::iterator i = minions.begin(); i != minions.end(); ++i)
             if (Creature* minion = instance->GetCreature(*i))
                 UpdateMinionState(minion, state);