From 36ddfdc7b959f7fc4000f6c3ff50aca65fbe3b2e Mon Sep 17 00:00:00 2001
From: wandererfan <wandererfan@gmail.com>
Date: Thu, 12 Feb 2026 16:29:09 -0500
Subject: [PATCH 1/2] [TD]fix crash on failed cut

- wrong result and warning on first time through.  Fixes itself after
  next execute().
- https://github.com/FreeCAD/FreeCAD/issues/27414
---
 src/Mod/TechDraw/App/DrawBrokenView.cpp | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/Mod/TechDraw/App/DrawBrokenView.cpp b/src/Mod/TechDraw/App/DrawBrokenView.cpp
index b6e540381c..6b5fb01dc5 100644
--- a/src/Mod/TechDraw/App/DrawBrokenView.cpp
+++ b/src/Mod/TechDraw/App/DrawBrokenView.cpp
@@ -173,7 +173,12 @@ TopoDS_Shape DrawBrokenView::breakShape(const TopoDS_Shape& shapeToBreak) const
     auto breaksAll = Breaks.getValues();
     TopoDS_Shape updatedShape = shapeToBreak;
     for (auto& item : breaksAll) {
+        TopoDS_Shape previousShape = updatedShape;
         updatedShape = apply1Break(*item, updatedShape);
+        if (updatedShape.IsNull()) {
+            Base::Console().warning("Failed to apply break %s\n", item->Label.getValue());
+            updatedShape = previousShape;
+        }
     }
     return updatedShape;
 }
@@ -198,20 +203,26 @@ TopoDS_Shape DrawBrokenView::apply1Break(const App::DocumentObject& breakObj, co
     moveDir0.Normalize();
     moveDir0 = DU::closestBasisOriented(moveDir0);
     auto halfSpace0 = makeHalfSpace(breakPoints.first, moveDir0, breakPoints.second);
+
     FCBRepAlgoAPI_Cut mkCut0(inShape, halfSpace0);
-    if (!mkCut0.IsDone()) {
-        Base::Console().message("DBV::apply1Break - cut0 failed\n");
+    if (!mkCut0.IsDone() || mkCut0.Shape().IsNull()) {
+        Base::Console().warning("Failed to make first cut for break %s.\n", breakObj.Label.getValue());
+        return {};
     }
+
     TopoDS_Shape cut0 = mkCut0.Shape();
+
     // make a halfspace that is positioned at the second breakpoint and extends
     // in the direction of the first point
     Base::Vector3d moveDir1 = breakPoints.first - breakPoints.second;
     moveDir1.Normalize();
     moveDir1 = DU::closestBasisOriented(moveDir1);
     auto halfSpace1 = makeHalfSpace(breakPoints.second, moveDir1, breakPoints.first);
+
     FCBRepAlgoAPI_Cut mkCut1(inShape, halfSpace1);
-    if (!mkCut1.IsDone()) {
-        Base::Console().message("DBV::apply1Break - cut1 failed\n");
+    if (!mkCut1.IsDone()|| mkCut1.Shape().IsNull()) {
+        Base::Console().warning("Failed to make second cut for break %s.\n", breakObj.Label.getValue());
+        return {};
     }
     TopoDS_Shape cut1 = mkCut1.Shape();
 

From 6d73f9173ccfeb2b840cda9b3f95b26cfbb57c17 Mon Sep 17 00:00:00 2001
From: wandererfan <wandererfan@gmail.com>
Date: Thu, 12 Feb 2026 16:46:19 -0500
Subject: [PATCH 2/2] [TD]use BRepAlgoAPI_Cut instead of FCBRepAlgoAPI_Cut

---
 src/Mod/TechDraw/App/DrawBrokenView.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/Mod/TechDraw/App/DrawBrokenView.cpp b/src/Mod/TechDraw/App/DrawBrokenView.cpp
index 6b5fb01dc5..dc2c4b9549 100644
--- a/src/Mod/TechDraw/App/DrawBrokenView.cpp
+++ b/src/Mod/TechDraw/App/DrawBrokenView.cpp
@@ -204,7 +204,10 @@ TopoDS_Shape DrawBrokenView::apply1Break(const App::DocumentObject& breakObj, co
     moveDir0 = DU::closestBasisOriented(moveDir0);
     auto halfSpace0 = makeHalfSpace(breakPoints.first, moveDir0, breakPoints.second);
 
-    FCBRepAlgoAPI_Cut mkCut0(inShape, halfSpace0);
+    // FCBRepAlgoAPI_Cut gets upset about cutting non-solids?? "XXX is not a solid" from Boolean::execute().
+    // We are cutting Compounds and that is valid in BRepAlgoAPI_Cut, but maybe not in FCBRepAlgoAPI_Cut?
+    // See sample file here: https://github.com/FreeCAD/FreeCAD/issues/27414
+    BRepAlgoAPI_Cut mkCut0(inShape, halfSpace0);
     if (!mkCut0.IsDone() || mkCut0.Shape().IsNull()) {
         Base::Console().warning("Failed to make first cut for break %s.\n", breakObj.Label.getValue());
         return {};
@@ -219,7 +222,8 @@ TopoDS_Shape DrawBrokenView::apply1Break(const App::DocumentObject& breakObj, co
     moveDir1 = DU::closestBasisOriented(moveDir1);
     auto halfSpace1 = makeHalfSpace(breakPoints.second, moveDir1, breakPoints.first);
 
-    FCBRepAlgoAPI_Cut mkCut1(inShape, halfSpace1);
+    // see mkCut0 above
+    BRepAlgoAPI_Cut mkCut1(inShape, halfSpace1);
     if (!mkCut1.IsDone()|| mkCut1.Shape().IsNull()) {
         Base::Console().warning("Failed to make second cut for break %s.\n", breakObj.Label.getValue());
         return {};