Not reproducible for me with Version: 7.3.0.0.alpha0+ / LibreOffice Community
Build ID: 5ab21caf603ba0a1c95bbc94a29eebe3483d1599
CPU threads: 8; OS: Linux 5.11; UI render: default; VCL: gtk3
Locale: fr-FR (fr_FR.UTF-8); UI: en-US
Ubuntu_20.04_x86-64
Calc: threaded

Did you reset the user profile? 
Have you deleted all lock files left over from a previous crash?

Status has been set to NEEDINFO, please set it back to UNCONFIRMED once requested information has been provided.

Best regards. JBF

@JBF  It's still happening for me using master build from 2021-10-14.

Maybe this depends on the specific graphic driver or hardware (?)  
I'm running xorg, not Wayland, in case that makes a difference.


> Did you reset the user profile? 

I thought that's what --safe-mode does, but to eliminate all doubt I completely removed $HOME/.config/libreofficedev and tried again.  I also removed all environment variables.  The commands were:

rm -rf $HOME/.config/libreofficedev
env -i DISPLAY=$DISPLAY \
/lotest/7.3.0.0.alpha0/opt/libreofficedev7.3/program/soffice --safe-mode

> Have you deleted all lock files left over from a previous crash?

Not sure where to look.  Can you point me to where lock files are stored?
Note that no specific document is being opened; LO is just started without arguments (or with only --safe-mode; I get the messages either way).

Version: 7.3.0.0.alpha0+ / LibreOffice Community
Build ID: c998691e22ceda15c89d55cf7005201f0392dadb
CPU threads: 12; OS: Linux 5.4; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US
TinderBox: Linux-rpm_deb-x86_64@86-TDF, Branch:master, Time: 2021-10-14_11:54:20
Calc: threaded

I haven't compile LO myself in ages; but grepping the code found that this message comes from tools/source/generic/poly.cxx  

void Polygon::Optimize( PolyOptimizeFlags nOptimizeFlags )
{
    DBG_ASSERT( !mpImplPolygon->mxFlagAry, "Optimizing could fail with beziers!" );
    ...
}

I attached a backtrace with symbols (from my own build from git).

It's tricky to get -- a hang occurs if gdb is running in a window in the same X session (I had to run gdb with XAUTHORITY and DISPLAY set from a vt to get it).

#0  0x00007fffeeeba010 in tools::Polygon::Optimize(PolyOptimizeFlags)@plt () at /home/jima/src/libreoffice/instdir/program/libvcllo.so
#1  0x00007fffefa7e212 in vcl::test::(anonymous namespace)::drawPolygonOffset(OutputDevice&, tools::Rectangle const&, int, int) (rDevice=..., rRect=..., nOffset=2, nFix=0)
    at /home/jima/src/libreoffice/vcl/backendtest/outputdevice/polygon.cxx:30
#2  0x00007fffefa7e323 in vcl::test::OutputDeviceTestPolygon::setupRectangle(bool) (this=0x7fffffffd340, bEnableAA=false) at /home/jima/src/libreoffice/vcl/backendtest/outputdevice/polygon.cxx:44
#3  0x00007fffefa87999 in GraphicsRenderTests::testDrawRectWithPolygon() (this=0x7fffffffd660) at /home/jima/src/libreoffice/vcl/backendtest/GraphicsRenderTests.cxx:119
#4  0x00007fffefab3394 in GraphicsRenderTests::runALLTests() (this=0x7fffffffd660) at /home/jima/src/libreoffice/vcl/backendtest/GraphicsRenderTests.cxx:2023
#5  0x00007fffefab3f09 in GraphicsRenderTests::run(bool) (this=0x7fffffffd660, storeResultBitmap=false) at /home/jima/src/libreoffice/vcl/backendtest/GraphicsRenderTests.cxx:2167
#6  0x00007ffff7c46282 in desktop::(anonymous namespace)::runGraphicsRenderTests() () at /home/jima/src/libreoffice/desktop/source/app/app.cxx:349
#7  0x00007ffff7c4b157 in desktop::Desktop::Main() (this=0x7fffffffdbd0) at /home/jima/src/libreoffice/desktop/source/app/app.cxx:1565
#8  0x00007fffef876c35 in ImplSVMain() () at /home/jima/src/libreoffice/vcl/source/app/svmain.cxx:199
#9  0x00007fffef876d62 in SVMain() () at /home/jima/src/libreoffice/vcl/source/app/svmain.cxx:231
#10 0x00007ffff7cb0f67 in soffice_main() () at /home/jima/src/libreoffice/desktop/source/app/sofficemain.cxx:98
#11 0x00005555555549ed in sal_main () at /home/jima/src/libreoffice/desktop/source/app/main.c:49
#12 0x00005555555549cf in main (argc=2, argv=0x7fffffffdf48) at /home/jima/src/libreoffice/desktop/source/app/main.c:47

*** Bug 145171 has been marked as a duplicate of this bug. ***