diff --git a/src/Mod/TechDraw/App/CenterLine.cpp b/src/Mod/TechDraw/App/CenterLine.cpp
index f467f5a802..80b7c02d62 100644
--- a/src/Mod/TechDraw/App/CenterLine.cpp
+++ b/src/Mod/TechDraw/App/CenterLine.cpp
@@ -43,6 +43,7 @@
 #include "CenterLinePy.h"
 
 using namespace TechDraw;
+using DU = DrawUtil;
 
 TYPESYSTEM_SOURCE(TechDraw::CenterLine, Base::Persistence)
 
@@ -108,8 +109,22 @@ CenterLine::CenterLine(Base::Vector3d pt1,
                        double h,
                        double v,
                        double r,
-                       double x) : CenterLine(BaseGeomPtrFromVectors(pt1, pt2), m, h, v, r, x)
+                       double x)
 {
+    m_start = pt1;
+    m_end = pt2;
+    m_mode = m;
+    m_hShift = h;
+    m_vShift = v;
+    m_rotate = r;
+    m_extendBy = x;
+    m_type = CLTYPE::FACE;
+    m_flip2Line = false;
+
+    m_geometry = BaseGeomPtrFromVectors(pt1, pt2);
+
+    initialize();
+
 }
 
 CenterLine::~CenterLine()
@@ -509,13 +524,28 @@ std::pair<Base::Vector3d, Base::Vector3d> CenterLine::calcEndPoints2Lines(DrawVi
     Base::Vector3d p2   = (l1p2 + l2p2) / 2.0;
     Base::Vector3d mid = (p1 + p2) / 2.0;
 
+    // if the proposed end points prevent the creation of a vertical or horizontal centerline, we need
+    // to prevent the "orientation" code below from creating identical endpoints.  This would create a
+    // zero length edge and cause problems later.
+    // this should probably be prevented in the creation task?
+    bool inhibitVertical = false;
+    bool inhibitHorizontal = false;
+    if (DU::fpCompare(p1.y, p2.y, EWTOLERANCE)) {
+        // proposed end points are aligned vertically, so we can't draw a vertical line to connect them
+        inhibitVertical = true;
+    }
+    if (DU::fpCompare(p1.x, p2.x, EWTOLERANCE)) {
+        // proposed end points are aligned horizontally, so we can't draw a horizontal line to connect them
+        inhibitHorizontal = true;
+    }
+
     //orientation
-    if (mode == 0) {           //Vertical
-            p1.x = mid.x;
-            p2.x = mid.x;
-    } else if (mode == 1) {    //Horizontal
-            p1.y = mid.y;
-            p2.y = mid.y;
+    if (mode == 0 && !inhibitVertical) {           //Vertical
+        p1.x = mid.x;
+        p2.x = mid.x;
+    } else if (mode == 1 && !inhibitHorizontal) {    //Horizontal
+        p1.y = mid.y;
+        p2.y = mid.y;
     } else if (mode == 2) {    //Aligned
         // no op
     }
diff --git a/src/Mod/TechDraw/App/Geometry.cpp b/src/Mod/TechDraw/App/Geometry.cpp
index eb487f8aa8..9786f2245d 100644
--- a/src/Mod/TechDraw/App/Geometry.cpp
+++ b/src/Mod/TechDraw/App/Geometry.cpp
@@ -283,6 +283,7 @@ std::vector<Base::Vector3d> BaseGeom::findEndPoints()
     } else {
         //TODO: this should throw something
         Base::Console().Message("Geometry::findEndPoints - OCC edge not found\n");
+        throw Base::RuntimeError("no OCC edge in Geometry::findEndPoints");
     }
     return result;
 }
diff --git a/src/Mod/TechDraw/App/GeometryMatcher.cpp b/src/Mod/TechDraw/App/GeometryMatcher.cpp
index 6d1f68c018..45b2baea8a 100644
--- a/src/Mod/TechDraw/App/GeometryMatcher.cpp
+++ b/src/Mod/TechDraw/App/GeometryMatcher.cpp
@@ -272,7 +272,7 @@ bool GeometryMatcher::compareEllipseArcs(TopoDS_Edge &edge1, TopoDS_Edge &edge2)
 // not sure how successful this would be.  For now, we just say it doesn't match
 bool GeometryMatcher::compareDifferent(TopoDS_Edge &edge1, TopoDS_Edge &edge2)
 {
-    Base::Console().Message("GM::compareDifferent()\n");
+//    Base::Console().Message("GM::compareDifferent()\n");
     BRepAdaptor_Curve adapt1(edge1);
     BRepAdaptor_Curve adapt2(edge2);
     return false;
diff --git a/src/Mod/TechDraw/Gui/TaskCenterLine.cpp b/src/Mod/TechDraw/Gui/TaskCenterLine.cpp
index 68110786de..94eae46cee 100644
--- a/src/Mod/TechDraw/Gui/TaskCenterLine.cpp
+++ b/src/Mod/TechDraw/Gui/TaskCenterLine.cpp
@@ -47,6 +47,7 @@
 using namespace Gui;
 using namespace TechDraw;
 using namespace TechDrawGui;
+using DU = DrawUtil;
 
 //ctor for edit
 TaskCenterLine::TaskCenterLine(TechDraw::DrawViewPart* partFeat,
@@ -190,6 +191,9 @@ void TaskCenterLine::setUiPrimary()
     ui->qsbRotate->setValue(qAngle);
     int precision = Base::UnitsApi::getDecimals();
     ui->qsbRotate->setDecimals(precision);
+
+    int orientation = checkPathologicalEdges(m_mode);
+    setUiOrientation(orientation);
 }
 
 void TaskCenterLine::setUiEdit()
@@ -292,26 +296,45 @@ void TaskCenterLine::onStyleChanged()
     m_partFeat->recomputeFeature();
 }
 
+// check that we are not trying to create an impossible centerline (ex a vertical centerline
+// between 2 horizontal edges)
+int TaskCenterLine::checkPathologicalEdges(int inMode)
+{
+    if (m_type != 1) {
+        // not an edge based centerline, this doesn't apply
+        return inMode;
+    }
+
+    TechDraw::BaseGeomPtr edge1 = m_partFeat->getEdge(m_subNames.front());
+    std::vector<Base::Vector3d> ends1 = edge1->findEndPoints();
+    bool edge1Vertical = DU::fpCompare(ends1.front().x, ends1.back().x, EWTOLERANCE);
+    bool edge1Horizontal = DU::fpCompare(ends1.front().y, ends1.back().y, EWTOLERANCE);
+
+    TechDraw::BaseGeomPtr edge2 = m_partFeat->getEdge(m_subNames.back());
+    std::vector<Base::Vector3d> ends2 = edge2->findEndPoints();
+    bool edge2Vertical = DU::fpCompare(ends2.front().x, ends2.back().x, EWTOLERANCE);
+    bool edge2Horizontal = DU::fpCompare(ends2.front().y, ends2.back().y, EWTOLERANCE);
+
+    if (edge1Vertical && edge2Vertical) {
+        return CenterLine::CLMODE::VERTICAL;
+    }
+    if (edge1Horizontal && edge2Horizontal) {
+        return CenterLine::CLMODE::HORIZONTAL;
+    }
+
+    // not pathological case, just return the input mode
+    return inMode;
+}
+
 //******************************************************************************
 void TaskCenterLine::createCenterLine()
 {
     Gui::Command::openCommand(QT_TRANSLATE_NOOP("Command", "Create CenterLine"));
 
+    m_mode = checkPathologicalEdges(m_mode);
+
     CenterLine* cl = CenterLine::CenterLineBuilder(m_partFeat, m_subNames, m_mode, false);
 
-    // the centerline creation can fail if m_type is edge and both selected edges are horizontal
-    // because we attempt by default to create a vertical centerline
-
-    if (!cl) { // try a horizontal line
-        cl = CenterLine::CenterLineBuilder(m_partFeat, m_subNames, CenterLine::CLMODE::HORIZONTAL, false);
-        if (cl) {
-            m_mode = CenterLine::CLMODE::HORIZONTAL;
-            ui->rbHorizontal->blockSignals(true);
-            ui->rbHorizontal->setChecked(true);
-            ui->rbHorizontal->blockSignals(false);
-        }
-    }
-
     if (!cl) {
         Gui::Command::abortCommand();
         return;
@@ -344,52 +367,41 @@ void TaskCenterLine::createCenterLine()
 
 void TaskCenterLine::updateOrientation()
 {
+    if (!m_cl) {
+        return;
+    }
     // When the orientation was changed, it can be that the centerline becomes invalid
     // this can lead to a crash, see e.g.
     // https://forum.freecad.org/viewtopic.php?f=35&t=44255&start=20#p503220
     // The centerline creation can fail if m_type is edge and both selected edges are vertical or horizontal.
-    // To test the validity before an existing centerline is changed, we create a new one with the desired parameters.
     int orientation = m_cl->m_mode;
-    if (!m_edgeName.empty()) { // we have an existing centerline, not a freshly created one
-        // since m_subNames is then empty, fill it with two times the centerline
-        // because the result of CenterLineBuilder will then in case of success again be the centerline
-        m_subNames.resize(2);
-        m_subNames[0] = m_edgeName;
-        m_subNames[1] = m_edgeName;
+    if (!m_edgeName.empty() && !m_cl->m_edges.empty()) {
+         // we have an existing centerline, not a freshly created one, and it is a centerline between edges
+        m_subNames = m_cl->m_edges;
+        orientation = checkPathologicalEdges(orientation);
     }
 
-    CenterLine* cl = CenterLine::CenterLineBuilder(m_partFeat, m_subNames, orientation, m_cl->m_flip2Line);
+    setUiOrientation(orientation);
 
-    if (!cl) { // try another orientation
-        if (orientation == CenterLine::CLMODE::VERTICAL)
-            orientation = CenterLine::CLMODE::HORIZONTAL;
-        else if (orientation == CenterLine::CLMODE::HORIZONTAL)
-            orientation = CenterLine::CLMODE::VERTICAL;
-        cl = CenterLine::CenterLineBuilder(m_partFeat, m_subNames, orientation, m_cl->m_flip2Line);
-        if (cl) {
-            if (orientation == CenterLine::CLMODE::VERTICAL) {
-                m_cl->m_mode = CenterLine::CLMODE::VERTICAL;
-                ui->rbVertical->blockSignals(true);
-                ui->rbVertical->setChecked(true);
-                // we know now that only vertical is possible
-                ui->rbHorizontal->setEnabled(false);
-                ui->rbVertical->blockSignals(false);
-            }
-            else if (orientation == CenterLine::CLMODE::HORIZONTAL) {
-                m_cl->m_mode = CenterLine::CLMODE::HORIZONTAL;
-                ui->rbHorizontal->blockSignals(true);
-                ui->rbHorizontal->setChecked(true);
-                ui->rbVertical->setEnabled(false);
-                ui->rbHorizontal->blockSignals(false);
-            }
-        }
+    m_partFeat->recomputeFeature();
+}
+
+void TaskCenterLine::setUiOrientation(int orientation)
+{
+    ui->rbVertical->blockSignals(true);
+    ui->rbVertical->blockSignals(true);
+
+    if (orientation == CenterLine::CLMODE::VERTICAL) {
+        ui->rbVertical->setChecked(true);
+        ui->rbHorizontal->setChecked(false);
+    } else if (orientation == CenterLine::CLMODE::HORIZONTAL) {
+        ui->rbVertical->setChecked(false);
+        ui->rbHorizontal->setChecked(true);
     }
 
-    if (cl) { // we succeeded
-        // reset the flip for existing centerline that might use the flip feature (when created with FC 0.19)
-        m_cl->m_flip2Line = false;
-        m_partFeat->recomputeFeature();
-    }
+    ui->rbVertical->blockSignals(false);
+    ui->rbVertical->blockSignals(false);
+
 }
 
 void TaskCenterLine::saveButtons(QPushButton* btnOK,
diff --git a/src/Mod/TechDraw/Gui/TaskCenterLine.h b/src/Mod/TechDraw/Gui/TaskCenterLine.h
index cdd1a0cbff..b725d79b17 100644
--- a/src/Mod/TechDraw/Gui/TaskCenterLine.h
+++ b/src/Mod/TechDraw/Gui/TaskCenterLine.h
@@ -88,6 +88,9 @@ protected:
     Qt::PenStyle getCenterStyle();
     double getExtendBy();
 
+    int checkPathologicalEdges(int inMode);
+    void setUiOrientation(int orientation);
+
 private:
     std::unique_ptr<Ui_TaskCenterLine> ui;