From d56038bc4c6d711f829cd2cde55d501622fb5ad7 Mon Sep 17 00:00:00 2001
From: PaddleStroke <pierrelouis.boyer@gmail.com>
Date: Tue, 23 Sep 2025 18:06:01 +0200
Subject: [PATCH] Assembly: Prevent crash when link to linkgroup in subassembly
 (#24125)

* Assembly: Prevent crash when link to linkgroup in subassembly

* ViewProviderAssembly: Additional crash failsafe.
---
 src/Mod/Assembly/App/AssemblyObject.cpp       | 5 +++++
 src/Mod/Assembly/Gui/ViewProviderAssembly.cpp | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/src/Mod/Assembly/App/AssemblyObject.cpp b/src/Mod/Assembly/App/AssemblyObject.cpp
index 5eb7267836..3be6e90d9c 100644
--- a/src/Mod/Assembly/App/AssemblyObject.cpp
+++ b/src/Mod/Assembly/App/AssemblyObject.cpp
@@ -997,6 +997,11 @@ AssemblyObject::getConnectedParts(App::DocumentObject* part,
 
         App::DocumentObject* obj1 = getMovingPartFromRef(this, joint, "Reference1");
         App::DocumentObject* obj2 = getMovingPartFromRef(this, joint, "Reference2");
+
+        if (!obj1 || !obj2) {
+            continue;
+        }
+
         if (obj1 == part) {
             auto* ref =
                 dynamic_cast<App::PropertyXLinkSub*>(joint->getPropertyByName("Reference2"));
diff --git a/src/Mod/Assembly/Gui/ViewProviderAssembly.cpp b/src/Mod/Assembly/Gui/ViewProviderAssembly.cpp
index 5c1216b94d..66b83809f7 100644
--- a/src/Mod/Assembly/Gui/ViewProviderAssembly.cpp
+++ b/src/Mod/Assembly/Gui/ViewProviderAssembly.cpp
@@ -794,6 +794,9 @@ ViewProviderAssembly::DragMode ViewProviderAssembly::findDragMode()
 {
     auto addPartsToMove = [&](const std::vector<Assembly::ObjRef>& refs) {
         for (auto& partRef : refs) {
+            if (!partRef.obj) {
+                continue;
+            }
             auto* pPlc =
                 dynamic_cast<App::PropertyPlacement*>(partRef.obj->getPropertyByName("Placement"));
             if (pPlc) {