View Issue Details

IDProjectCategoryView StatusLast Update
0002461PartDesignBugpublic2022-01-24 19:16
Reportertaiyo_uk Assigned To 
Status confirmedResolutionopen 
Platformx86_64OSWindowsOS VersionWindows 7 64 bit
Product Version0.15 
Target Version0.20 
Summary0002461: Crash when creating loft between two sketches
DescriptionCrating a loft between two sketches causes FreeCAD to segfault in Fedora 23 x86_64, and to produce this error in Windows 7 64-bit: "ACCESS VIOLATION at address 0x00000010 during 'READ' operation"

This only happens for certain sketches such as those included in the attached file.
Steps To Reproduce1. Open the attached file in FreeCAD
2. Create a loft using the two sketches
3. The crash happens when clicking the OK button in the loft dialog.
Additional InformationChanging the order of the two sketches has no effect. Selecting the closed option produces a different error in Windows: "TCollection_DataMap::ChangeFind"
Tags#ready-for-migration, OCC 7.3, OCC Bug, upstream
FreeCAD Information



2016-03-02 11:10


loft-test-1.FCStd (Attachment missing)


2016-03-02 11:20

reporter   ~0006877

Version information:

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.15.4671 (Git)
Branch: releases/FreeCAD-0-15
Hash: 244b3aef360841646cbfe80a1b225c8b39c8380c
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17


2016-03-03 07:22

reporter   ~0006879

The same problem happens on the latest (at the time of writing) git build, this is what happens on Fedora:

*** Abort *** an exception was raised, but no catch was found.
    ... The exception is:SIGSEGV 'segmentation violation' detected. Address 0

Version information:

OS: Linux
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6538 (Git)
Build type: Release
Branch: master
Hash: 57c783e5b0f4da8611f5b1f26dc7499a5979e574
Python version: 2.7.10
Qt version: 4.8.7
Coin version: 3.1.3


2016-03-06 20:04

manager   ~0006888

Last edited: 2016-03-06 20:05

I can confirm the problem here.

OS: Ubuntu 14.04.4 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6557 (Git)
Build type: None
Branch: master
Hash: 948ccac021b15aff3c7a3b033c508e7ec9b123d6
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

But I suspect this is due to your sketches having a different number of segments - this is bound for trouble when creating lofts. This is probably an OCC issue (the geometric kernel FreeCAD uses) that the FreeCAD devs have no control of.

A workaround is to add very short line segments to the second sketch so it has the same number of segments as the first sketch. Then the loft succeeds (see attached "loft-test_normandc1.fcstd" file). Another would be to create this model in two separate operations: first create a prism of the outer volume with a Pad, then create a loft representing the volume you want to be cut from the prism, and apply a boolean cut. This way the model will have planar faces rather than BSpline ones on which sketches cannot be mapped.

Next time, please report modeling issues to the FreeCAD forum first, so to determine if it's a FreeCAD bug, or a bug in OCC which the devs can't do anything about.

I wonder if the crash can be avoided, and an error thrown instead.


2016-03-06 20:05


loft-test_normandc1.FCStd (Attachment missing)


2017-01-26 21:55

administrator   ~0008002

Forum thread:


2017-12-15 20:36

administrator   ~0010608

@taiyo_uk do you still have the attachment for this ticket? Bugtracker shows it's missing.


2018-01-18 14:25

administrator   ~0010789

@taiyo_uk ping


2018-06-08 23:53

reporter   ~0011373

Last edited: 2018-06-08 23:53

Ran into the same problem, apparently it still exists in 0.17. How to reproduce: Go to Part Design workbench, load attached file, create an additive loft, add sections from top to bottom. FreeCAD should crash with a segmentation fault.

OS: "Manjaro Linux"
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13522 (Git) AppImage
Build type: None
Branch: releases/FreeCAD-0-17
Hash: 3bb5ff4e70c0c526f2d9dd69b1004155b2f527f2
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedKingdom (en_GB)

Also tested on a friend's Mac, which crasches too:

OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13519 (Git)
Build type: Release
Branch: (HEAD detached at 1a8b868)
Hash: 1a8b868018f45ea486c0023fdbfeb06febc1fb89
Python version: 2.7.14
Qt version: 5.10.1
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/Austria (en_AT)

loft-sigsegv.fcstd (13,153 bytes)


2018-06-08 23:58

administrator   ~0011374

@hirnsalat Thanks for testing. Can you also test with OCC7.3 when it becomes available ?
Also please also report your findings to the dedicated forum thread


2018-09-30 15:27

administrator   ~0011876

That's a regression in OCCT 7.2. When using OCCT 7.0 it doesn't create a loft but reports an appropriate error message and does not crash.


2019-01-20 20:04

reporter   ~0012473

Is this issue resolved now? or is there another "exceptions in occt" ticket that can replace this?


2019-01-20 21:01

administrator   ~0012474

It was hirnsalat you said that it crashes with OCCT 7.2. But I've just tested it and I get it working when I also select the Ruled surface option. Without it an error message pops up but I don't get a crash. I have tested this with OCCT 7.0 and 7.2.


2019-02-09 20:16

manager   ~0012598

I get a crash when I add the third section with the version below using OCC 7.3.0.

Program received signal SIGSEGV, Segmentation fault.
#0  /lib/x86_64-linux-gnu/ [0x7f7bc5f14f20]
#1  /usr/lib/x86_64-linux-gnu/ [0x7f7b7e043cb5]
0000002  0x7f7b7e04477e in BRepLib::EncodeRegularity(TopoDS_Shape const&, double) from /usr/lib/x86_64-linux-gnu/
0000003  0x7f7b7cd22da8 in BRepOffsetAPI_ThruSections::Build() from /usr/lib/x86_64-linux-gnu/
0000004  0x7f7b1e4a3c2b in PartDesign::Loft::execute() from /home/normand2/compilation/FreeCAD/freecad-build2/Mod/PartDesign/
0000005  0x7f7bc83c3265 in App::DocumentObject::recompute() from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000006  0x7f7b827aabdb in Part::Feature::recompute() from /home/normand2/compilation/FreeCAD/freecad-build2/Mod/Part/
0000007  0x7f7bc8377544 in App::Document::_recomputeFeature(App::DocumentObject*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000008  0x7f7bc837f013 in App::Document::recomputeFeature(App::DocumentObject*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000009  0x7f7b1e0691d0 in PartDesignGui::TaskLoftParameters::onSelectionChanged(Gui::SelectionChanges const&) from /home/normand2/compilation/FreeCAD/freecad-build2/Mod/PartDesign/
0000010  0x7f7bc8ed09c6 in Gui::SelectionObserver::_onSelectionChanged(Gui::SelectionChanges const&) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000011  0x7f7bc8edebbf in boost::signals2::detail::signal_impl<void (Gui::SelectionChanges const&), boost::signals2::optional_last_value<void>, int, std::less<int>, boost::function<void (Gui::SelectionChanges const&)>, boost::function<void (boost::signals2::connection const&, Gui::SelectionChanges const&)>, boost::signals2::mutex>::operator()(Gui::SelectionChanges const&) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000012  0x7f7bc8ed8f81 in Gui::SelectionSingleton::addSelection(char const*, char const*, char const*, float, float, float) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000013  0x7f7bc8d4237a in Gui::SoFCUnifiedSelection::handleEvent(SoHandleEventAction*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000014  0x7f7bc5722504 in SoAction::traverse(SoNode*) from /usr/lib/x86_64-linux-gnu/
0000015  0x7f7bc58c2008 in SoChildList::traverse(SoAction*, int, int) from /usr/lib/x86_64-linux-gnu/
0000016  0x7f7bc59114e6 in SoGroup::doAction(SoAction*) from /usr/lib/x86_64-linux-gnu/
0000017  0x7f7bc592b967 in SoSeparator::doAction(SoAction*) from /usr/lib/x86_64-linux-gnu/
0000018  0x7f7bc5722504 in SoAction::traverse(SoNode*) from /usr/lib/x86_64-linux-gnu/
0000019  0x7f7bc572be48 in SoHandleEventAction::beginTraversal(SoNode*) from /usr/lib/x86_64-linux-gnu/
0000020  0x7f7bc5722a82 in SoAction::apply(SoNode*) from /usr/lib/x86_64-linux-gnu/
0000021  0x7f7bc58de8a0 in SoEventManager::actuallyProcessEvent(SoEvent const*) from /usr/lib/x86_64-linux-gnu/
0000022  0x7f7bc8db590e in SIM::Coin3D::Quarter::QuarterWidget::processSoEvent(SoEvent const*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000023  0x7f7bc8dbe5c6 in SIM::Coin3D::Quarter::SoQTQuarterAdaptor::processSoEvent(SoEvent const*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000024  0x7f7bc8de8179 in Gui::View3DInventorViewer::processSoEventBase(SoEvent const*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000025  0x7f7bc8dd118e in Gui::GestureNavigationStyle::processSoEvent(SoEvent const*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000026  0x7f7bc8dc8418 in Gui::NavigationStyle::processEvent(SoEvent const*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000027  0x7f7bc8de80f3 in Gui::View3DInventorViewer::processSoEvent(SoEvent const*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000028  0x7f7bc8dacd45 in SIM::Coin3D::Quarter::EventFilter::eventFilter(QObject*, QEvent*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000029  0x7f7bc6af268c in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
0000030  0x7f7bc7107805 in QApplicationPrivate::notify_helper(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
0000031  0x7f7bc710f64f in QApplication::notify(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
0000032  0x7f7bc8b88a48 in Gui::GUIApplication::notify(QObject*, QEvent*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000033  0x7f7bc6af29a8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
0000034  0x7f7bc710e622 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) from /usr/lib/x86_64-linux-gnu/
0000035  /usr/lib/x86_64-linux-gnu/ [0x7f7bc716114b]
0000036  /usr/lib/x86_64-linux-gnu/ [0x7f7bc71637ba]
0000037  0x7f7bc710782c in QApplicationPrivate::notify_helper(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
0000038  0x7f7bc710f0f4 in QApplication::notify(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
#39  0x7f7bc8b88a48 in Gui::GUIApplication::notify(QObject*, QEvent*) from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
#40  0x7f7bc6af29a8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) from /usr/lib/x86_64-linux-gnu/
0000041  0x7f7bc2a1d523 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) from /usr/lib/x86_64-linux-gnu/
0000042  0x7f7bc2a1eff5 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) from /usr/lib/x86_64-linux-gnu/
0000043  0x7f7bc29f62eb in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) from /usr/lib/x86_64-linux-gnu/
0000044  /usr/lib/x86_64-linux-gnu/ [0x7f7bb615a1c0]
0000045  /usr/lib/x86_64-linux-gnu/ [0x7f7bc0d74387]
0000046  /usr/lib/x86_64-linux-gnu/ [0x7f7bc0d745c0]
0000047  /usr/lib/x86_64-linux-gnu/ [0x7f7bc0d7464c]
0000048  0x7f7bc6b4b8ef in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) from /usr/lib/x86_64-linux-gnu/
0000049  0x7f7bc6af09ea in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) from /usr/lib/x86_64-linux-gnu/
0000050  0x7f7bc6af9a84 in QCoreApplication::exec() from /usr/lib/x86_64-linux-gnu/
0000051  0x7f7bc8b0dfab in Gui::Application::runApplication() from /home/normand2/compilation/FreeCAD/freecad-build2/lib/
0000052  ./FreeCAD(main+0x6ad) [0x5588702ee48d]
0000053  /lib/x86_64-linux-gnu/ [0x7f7bc5ef7b97]
0000054  ./FreeCAD(_start+0x2a) [0x5588702ef1ea]
OS: Ubuntu 18.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15816 (Git)
Build type: Release
Branch: master
Hash: 7ee0e4d43909ec688299b8498b240cccf8362c47
Python version: 3.6.7
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: French/Canada (fr_CA)


2019-02-09 20:21

manager   ~0012599

No crash with OCC 7.1.0 with this version. An error message appears in a pop up when pressing OK:
BRepFill :: profiles are inconsistent

OS: Ubuntu 18.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13509 (Git) AppImage
Build type: None
Branch: master
Hash: 0258808ccb6ba3bd5ea9312f79cd023f1a8671b7
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: French/Canada (fr_CA)


2019-02-23 20:29

administrator   ~0012734

I don't have OCCT 7.3 to this but according to the call stack this anyway must be a bug in OCCT, then.


2022-03-03 13:55

administrator   ~0016477

This ticket has been migrated to GitHub as issue 5642.

Issue History

Date Modified Username Field Change
2016-03-02 11:10 taiyo_uk New Issue
2016-03-02 11:10 taiyo_uk File Added: loft-test-1.FCStd
2016-03-02 11:20 taiyo_uk Note Added: 0006877
2016-03-03 07:22 taiyo_uk Note Added: 0006879
2016-03-06 20:04 normandc Note Added: 0006888
2016-03-06 20:05 normandc Note Edited: 0006888
2016-03-06 20:05 normandc File Added: loft-test_normandc1.FCStd
2017-01-26 21:53 Kunda1 Tag Attached: OCC Bug
2017-01-26 21:53 Kunda1 Tag Attached: upstream
2017-01-26 21:55 Kunda1 Note Added: 0008002
2017-12-15 20:36 Kunda1 Note Added: 0010608
2017-12-15 20:36 Kunda1 Status new => feedback
2018-01-18 14:25 Kunda1 Note Added: 0010789
2018-06-08 23:53 hirnsalat File Added: loft-sigsegv.fcstd
2018-06-08 23:53 hirnsalat Note Added: 0011373
2018-06-08 23:53 hirnsalat Note Edited: 0011373
2018-06-08 23:58 Kunda1 Note Added: 0011374
2018-06-08 23:58 Kunda1 Status feedback => confirmed
2018-06-08 23:58 Kunda1 Target Version => 0.18
2018-06-08 23:59 Kunda1 Tag Attached: OCC 7.3
2018-09-30 15:27 wmayer Note Added: 0011876
2019-01-20 20:04 maiden Note Added: 0012473
2019-01-20 21:01 wmayer Note Added: 0012474
2019-02-09 20:16 normandc Note Added: 0012598
2019-02-09 20:21 normandc Note Added: 0012599
2019-02-14 21:33 wmayer Project FreeCAD => PartDesign
2019-02-23 20:29 wmayer Target Version 0.18 => 0.19
2019-02-23 20:29 wmayer Note Added: 0012734
2021-02-06 06:43 abdullah Target Version => 0.20
2022-01-24 19:16 Kunda1 Tag Attached: #ready-for-migration