I also experience the segfault on exit on Arch Linux, since version 4.0. Also happened in the week before 4.0 release when I was running it from master (git). Everything else is working fine.

System is up-to-date and no foreign (dropped from official repo) packages, my DE is KDE. Note that Qt version here is 5.10.1. As I am running it from the repos I cannot generate a proper stracktrace. Let me know if giving one will be helpful to finding the problem. I will compile it without stripping symbols then.

I attached some info that may help finding the issue below, hopefully it helps finding the problem.

Thank you!



-- System info

Krita
  Version: 4.0.0

OS Information
  Build ABI: x86_64-little_endian-lp64
  Build CPU: x86_64
  CPU: x86_64
  Kernel Type: linux
  Kernel Version: 4.14.24-rt19-1-rt
  Pretty Productname: Arch Linux
  Product Type: arch
  Product Version: unknown

OpenGL Info 
  Vendor:  NVIDIA Corporation 
  Renderer:  "GeForce GTX TITAN Black/PCIe/SSE2" 
  Version:  "4.6.0 NVIDIA 390.42" 
  Shading language:  4.60 NVIDIA 
  Requested format:  QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::SwapBehavior(DoubleBuffer), swapInterval 0, colorSpace QSurfaceFormat::ColorSpace(DefaultColorSpace), profile  QSurfaceFormat::OpenGLContextProfile(CompatibilityProfile)) 
  Current format:    QSurfaceFormat(version 4.6, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 0, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::SwapBehavior(DoubleBuffer), swapInterval 0, colorSpace QSurfaceFormat::ColorSpace(DefaultColorSpace), profile  QSurfaceFormat::OpenGLContextProfile(CompatibilityProfile)) 
     Version: 4.6
     Supports deprecated functions true 
     is OpenGL ES: false 



-- Terminal output (LC_ALL=C I use for OpenColorIO workaround as mentioned on docs.krita.org)

$ LC_ALL=C krita
Setting XDG_DATA_DIRS "/usr/bin/../share:/usr/share:/usr/share:/usr/local/share"
Override language: ""
OpenGL Info 
  Vendor:  NVIDIA Corporation 
  Renderer:  "GeForce GTX TITAN Black/PCIe/SSE2" 
  Version:  "4.6.0 NVIDIA 390.42" 
  Shading language:  4.60 NVIDIA 
  Requested format:  QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::SwapBehavior(DoubleBuffer), swapInterval 0, colorSpace QSurfaceFormat::ColorSpace(DefaultColorSpace), profile  QSurfaceFormat::OpenGLContextProfile(CompatibilityProfile)) 
  Current format:    QSurfaceFormat(version 4.6, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 0, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::SwapBehavior(DoubleBuffer), swapInterval 0, colorSpace QSurfaceFormat::ColorSpace(DefaultColorSpace), profile  QSurfaceFormat::OpenGLContextProfile(CompatibilityProfile)) 
     Version: 4.6
     Supports deprecated functions true 
     is OpenGL ES: false 
krita has opengl true
Available translations QSet("es", "fa", "sv", "lt", "pl", "fr", "nn", "se", "vi", "it", "kk", "lv", "en_US", "sq", "he", "be", "eo", "ca", "da", "en_GB", "ia", "pt_BR", "km", "zh_CN", "zh_TW", "ta", "hr", "ug", "el", "tg", "et", "ms", "nds", "uk", "nl", "xh", "af", "wa", "uz", "pa", "ar", "ast", "pt", "ro", "cs", "sl", "fi", "br", "mai", "hi", "cy", "sk", "ja", "hu", "fy", "ca@valencia", "mk", "nb", "ko", "oc", "ru", "uz@cyrillic", "is", "th", "de", "tr", "ne", "hne", "bs", "mr", "bg", "ga", "eu", "gl")
Available domain translations QSet("es", "fa", "sv", "lt", "pl", "fr", "nn", "se", "vi", "it", "kk", "lv", "en_US", "sq", "he", "be", "eo", "ca", "da", "en_GB", "ia", "pt_BR", "km", "zh_CN", "zh_TW", "ta", "hr", "ug", "el", "tg", "et", "ms", "nds", "uk", "nl", "xh", "af", "wa", "uz", "pa", "ar", "ast", "pt", "ro", "cs", "sl", "fi", "br", "mai", "hi", "cy", "sk", "ja", "hu", "fy", "ca@valencia", "mk", "nb", "ko", "oc", "ru", "uz@cyrillic", "is", "th", "de", "tr", "ne", "hne", "bs", "mr", "bg", "ga", "eu", "gl")
Qt UI languages ("en-GB", "en-US") "en_GB.UTF-8"
Invalid profile :  "/usr/share/color/icc/colord/Crayons.icc" "Crayon Colors"
Invalid profile :  "/usr/share/color/icc/colord/x11-colors.icc" "X11 Colors"
QLayout: Attempting to add QLayout "" to QWidget "", which already has a layout
input profiles were read from ' /home/melvin/.local/share/krita/input '.
Loading Python plugin
"/usr/lib/libpython3.6m.so.1.0" true
Creating s_pythonLibrary /usr/lib/libpython3.6m.so
Found krita-python-libs at "/usr/lib/krita-python-libs"
Setting python paths: "/home/melvin/.local/share/krita/:/usr/share/krita/:/home/melvin/.local/share/krita/pykrita/:/usr/share/krita/pykrita/:/usr/share/pykrita/:/usr/lib/krita-python-libs"
/usr/lib/krita-python-libs/krita added to PYTHONPATH
Button KoToolBoxButton(0x55b2d8139f10, name="PathTool") has a conflicting priority
        falling back on QIcon::FromTheme: "edit-clear-locationbar-rtl"
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/preset-switcher
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/opacity-decrease
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/opacity-increase
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/lightness-increase
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/lightness-decrease
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/zoom-in
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/rotate-canvas-left
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/rotation-reset
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/rotate-canvas-right
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/zoom-out
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/brushsize-decrease
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/brushsize-increase
file:///usr/lib/qt/qml/org/krita/sketch/components/Button.qml:84:9: QML Image: Failed to get image from provider: image://icon/edit-clear
QFileSystemWatcher::removePaths: list is empty
QFileSystemWatcher::removePaths: list is empty
KCrash: crashing... crashRecursionCounter = 2
KCrash: Application Name = krita path = /usr/bin pid = 14532
KCrash: Arguments: /usr/bin/krita 
KCrash: Attempting to start /usr/lib/drkonqi from kdeinit
sock_file=/run/user/1000/kdeinit5__0
[1]  + 14532 suspended (signal)  LC_ALL=C krita

<here I must open the systray DrKonqi and click "close" so it resumes with coredump>

$ QSocketNotifier: Invalid socket 8 and type 'Read', disabling...
QSocketNotifier: Invalid socket 26 and type 'Read', disabling...
QSocketNotifier: Invalid socket 25 and type 'Read', disabling...
Unable to start Dr. Konqi
Re-raising signal for core dump handling.

[1]  + 14532 segmentation fault (core dumped)  LC_ALL=C krita



-- gdb gives the following "backtrace" summary

[Thread 0x7fff919f5700 (LWP 14657) exited]
[Thread 0x7fff8bfff700 (LWP 14658) exited]
[Thread 0x7fffe2017700 (LWP 14651) exited]
QFileSystemWatcher::removePaths: list is empty
QFileSystemWatcher::removePaths: list is empty
[Thread 0x7fffbcf19700 (LWP 14655) exited]

Thread 1 "krita" received signal SIGSEGV, Segmentation fault.
0x00007fffee4a2e39 in sem_wait@@GLIBC_2.2.5 () from /usr/lib/libpthread.so.0
(gdb) backtrace
#0  0x00007fffee4a2e39 in sem_wait@@GLIBC_2.2.5 () at /usr/lib/libpthread.so.0
#1  0x00007fffb55f4f26 in PyThread_acquire_lock_timed () at /usr/lib/libpython3.6m.so.1.0
#2  0x00007fffb56eb0cd in  () at /usr/lib/libpython3.6m.so.1.0
#3  0x00007fffb5581d56 in  () at /usr/lib/libpython3.6m.so.1.0
#4  0x00007fffb4b24345 in  () at /usr/lib/python3.6/site-packages/sip.so
#5  0x00007fffb4883ce7 in sipDockWidgetFactoryBase::~sipDockWidgetFactoryBase() () at /usr/lib/krita-python-libs/PyKrita/krita.so
#6  0x00007fffb4883d0a in sipDockWidgetFactoryBase::~sipDockWidgetFactoryBase() () at /usr/lib/krita-python-libs/PyKrita/krita.so
#7  0x00007ffff19686be in KoDockRegistry::~KoDockRegistry() () at /usr/lib/libkritaflake.so.16
#8  0x00007ffff19687da in  () at /usr/lib/libkritaflake.so.16
#9  0x00007ffff479f448 in __run_exit_handlers () at /usr/lib/libc.so.6
#10 0x00007ffff479f49a in  () at /usr/lib/libc.so.6
#11 0x00007ffff4788f51 in __libc_start_main () at /usr/lib/libc.so.6
#12 0x0000555555845efa in _start ()



-- finally, drkonqi will give the following

Application: krita (krita), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f8072525800 (LWP 14709))]

Thread 3 (Thread 0x7f8037ce6700 (LWP 14716)):
#0  0x00007f8068a5d3bd in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007f806f3a65bd in __gthread_cond_wait (__mutex=<optimized out>, __cond=<optimized out>) at /build/gcc/src/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu/bits/gthr-default.h:864
#2  0x00007f806f3a65bd in std::condition_variable::wait(std::unique_lock<std::mutex>&) (this=<optimized out>, __lock=...) at /build/gcc/src/gcc/libstdc++-v3/src/c++11/condition_variable.cc:53
#3  0x00007f80247a2d09 in  () at /usr/lib/libQt5WebKit.so.5
#4  0x00007f80247a2e59 in  () at /usr/lib/libQt5WebKit.so.5
#5  0x00007f806f3acb9f in std::execute_native_thread_routine(void*) (__p=0x55d05fe996f0) at /build/gcc/src/gcc/libstdc++-v3/src/c++11/thread.cc:83
#6  0x00007f8068a5708c in start_thread () at /usr/lib/libpthread.so.0
#7  0x00007f806ee1ae7f in clone () at /usr/lib/libc.so.6

Thread 2 (Thread 0x7f805235d700 (LWP 14712)):
#0  0x00007f806ee1097b in poll () at /usr/lib/libc.so.6
#1  0x00007f8066ec3ff3 in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007f8066ec410e in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#3  0x00007f806f973314 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#4  0x00007f806f9153db in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#5  0x00007f806f7247ae in QThread::exec() () at /usr/lib/libQt5Core.so.5
#6  0x00007f8068c82416 in  () at /usr/lib/libQt5DBus.so.5
#7  0x00007f806f729b4d in  () at /usr/lib/libQt5Core.so.5
#8  0x00007f8068a5708c in start_thread () at /usr/lib/libpthread.so.0
#9  0x00007f806ee1ae7f in clone () at /usr/lib/libc.so.6

Thread 1 (Thread 0x7f8072525800 (LWP 14709)):
[KCrash Handler]
#6  0x00007f8068a5fe39 in sem_wait@@GLIBC_2.2.5 () at /usr/lib/libpthread.so.0
#7  0x00007f802fb98f26 in PyThread_acquire_lock_timed () at /usr/lib/libpython3.6m.so.1.0
#8  0x00007f802fc8f0cd in  () at /usr/lib/libpython3.6m.so.1.0
#9  0x00007f802fb25d56 in  () at /usr/lib/libpython3.6m.so.1.0
#10 0x00007f802f108345 in  () at /usr/lib/python3.6/site-packages/sip.so
#11 0x00007f802ee67ce7 in sipDockWidgetFactoryBase::~sipDockWidgetFactoryBase() () at /usr/lib/krita-python-libs/PyKrita/krita.so
#12 0x00007f802ee67d0a in sipDockWidgetFactoryBase::~sipDockWidgetFactoryBase() () at /usr/lib/krita-python-libs/PyKrita/krita.so
#13 0x00007f806bf256be in KoDockRegistry::~KoDockRegistry() () at /usr/lib/libkritaflake.so.16
#14 0x00007f806bf257da in  () at /usr/lib/libkritaflake.so.16
#15 0x00007f806ed5c448 in __run_exit_handlers () at /usr/lib/libc.so.6
#16 0x00007f806ed5c49a in  () at /usr/lib/libc.so.6
#17 0x00007f806ed45f51 in __libc_start_main () at /usr/lib/libc.so.6
#18 0x000055d0544f0efa in _start ()