crash modifying thread in 26.3

Problem description

In the 26.3 weekly FC crashes when I modify the thread size in a particular model. In the 1.1.3 release the change causes no problem. I tried to derive a smaller test case but after deleting other bodies (imported kicad board and screws from Fastener WB) the problem disappears, and even remains gone if I undo these deletions and repeat the thread diameter change.

Workbench affected?

None

Steps to reproduce

open the attached model and change the thread size of "Hole_M1_center" of body Cooler_v3 to something else than M1.2 (say M1). After some time, apparently after finishing most computations, FC 26.3 will crash. It seems to be related to recursive redraw, but in safe mode it doesn't happen, thus I'm not sure if an addon is involved.

Expected behavior

thread updated as desired

debug.zip

Actual behavior

4e-08 <App> Document.cpp(2875): Recursive calling of recompute for document Hidra_RF_3x2_v3_mechSketch1
Program received signal SIGSEGV, Segmentation fault.
#0  /lib64/libc.so.6(+0x43190) [0x7f256ac43190]
#1  0x7f256b6c9c3d in QObjectPrivate::maybeSignalConnected(unsigned int) const from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0xd
#2  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6(+0x3164cf) [0x7f256b7164cf]
#3  0x7f256ca5729a in QComboBox::textActivated(QString const&) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0x3a
#4  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6(+0x4820ff) [0x7f256ca820ff]
#5  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6(+0x4ea407) [0x7f256caea407]
#6  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6(+0x31684a) [0x7f256b71684a]
#7  0x7f256ca574f7 in QComboBoxPrivateContainer::itemSelected(QModelIndex const&) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0x37
#8  0x7f256ca6c482 in QComboBoxPrivateContainer::eventFilter(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0x162
#9  0x7f256b75f8de in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0x7e
#10  0x7f256cbb3e38 in QApplicationPrivate::notify_helper(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0x78
#11  0x7f256cbb4cbd in QApplication::notify(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0xdad
#12  0x7f2571737038 in Gui::GUIApplication::notify(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libFreeCADGui.so+0x78
#13  0x7f256b75fb8a in QCoreApplication::notifyInternal2(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0x17a
#14  0x7f256cbbbe7c in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool, bool) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0x1ec
#15  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6(+0x5bee09) [0x7f256cbbee09]
#16  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6(+0x5c5440) [0x7f256cbc5440]
#17  0x7f256cbb3e48 in QApplicationPrivate::notify_helper(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Widgets.so.6+0x88
#18  0x7f2571737038 in Gui::GUIApplication::notify(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libFreeCADGui.so+0x78
#19  0x7f256b75fb8a in QCoreApplication::notifyInternal2(QObject*, QEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0x17a
#20  0x7f256bdd1970 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Gui.so.6+0x810
#21  0x7f256be31e14 in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Gui.so.6+0xb4
#22  /tmp/.mount_FreeCAmFbAOm/usr/lib/qt6/plugins/platforms/../../../libQt6XcbQpa.so.6(+0x58f90) [0x7f256706ef90]
#23  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/./libglib-2.0.so.0(+0x5bde6) [0x7f2568d06de6]
#24  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/./libglib-2.0.so.0(+0x5f0a7) [0x7f2568d0a0a7]
#25  /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/./libglib-2.0.so.0(g_main_context_iteration+0x2e) [0x7f2568d0a81e]
#26  0x7f256b4f6b12 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0x72
#27  0x7f256b79747c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0x25c
#28  0x7f256b7977da in QCoreApplication::exec() from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libQt6Core.so.6+0x9a
#29  0x7f257169ad19 in Gui::Application::runApplication() from /tmp/.mount_FreeCAmFbAOm/usr/bin/../lib/libFreeCADGui.so+0xe59
#30  /tmp/.mount_FreeCAmFbAOm/usr/bin/freecad(+0x9a79) [0x562ccc271a79]
#31  /lib64/libc.so.6(+0x2b4fe) [0x7f256ac2b4fe]
#32  /lib64/libc.so.6(__libc_start_main+0x8d) [0x7f256ac2b62b]
#33  /tmp/.mount_FreeCAmFbAOm/usr/bin/freecad(+0x8a69) [0x562ccc270a69]

Development version About Info (in Safe Mode)

OS: openSUSE Tumbleweed (KDE/plasma6/xcb)
Architecture: x86_64
Version: 26.3.0dev.20260902 (Git shallow) AppImage
Build date: 2026/09/02 02:30:22
Build type: Release
Branch: (HEAD detached at c68c45227)
Hash: c68c452275ec188f35c02f6b30aba880b3783cf1
Python 3.11.14, Qt 6.8.3, Coin 4.0.10 (bundled), Pivy 0.6.11 (bundled), Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, Clipper2 , IfcOpenShell 0.8.0, OCC 7.8.1
Locale: C/Default (C)
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Light/
QPA/File dialog/Color dialog: xcb/via Qt/via Qt
Navigation Style/Orbit Style/Rotation Mode: CAD/Rounded Arcball/Window center
Logical DPI/Physical DPI/Pixel Ratio: 96/127.628/1
OpenGL version/vendor/renderer: 4.6 (Compatibility Profile) Mesa 26.1.5/AMD/AMD Radeon Graphics (radeonsi, renoir, ACO, DRM 3.64, 7.1.4-1-default)

Last known good version (optional)

1.1.3 does't show this. 

In safe mode the 26.3 weekly also doesn't crash, though it throws many errors 
"PropertyPythonObject::Restore: blocked import of module 'FastenersCmd' during document restore. Only modules from FreeCAD or installed addons are permitted.
<string>(1)<class 'ImportError'>: module not permitted: FastenersCmd"
and a final
4e-08 <App> Document.cpp(2875): Recursive calling of recompute for document Hidra_RF_3x2_v3_mechSketch_badM1

All objects (kicad import and screws) show up normally i safe mode and the thread update also succeeds.