View Issue Details

IDProjectCategoryView StatusLast Update
0002461FreeCADBugpublic2018-09-30 15:27
Reportertaiyo_ukAssigned To 
Status confirmedResolutionopen 
Platformx86_64OSWindowsOS VersionWindows 7 64 bit
Product Version0.15 
Target Version0.18Fixed in Version 
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"
TagsOCC 7.3, OCC Bug, upstream



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

View 2 revisions

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

manager   ~0008002

Forum thread:


2017-12-15 20:36

manager   ~0010608

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


2018-01-18 14:25

manager   ~0010789

@taiyo_uk ping


2018-06-08 23:53

reporter   ~0011373

Last edited: 2018-06-08 23:53

View 2 revisions

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

manager   ~0011374

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


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.

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 View Revisions
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 View Revisions
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