Call is e.g. 

/Applications/LibreOffice.app/Contents/MacOS/soffice --convert-to pdf --safe-mode --headless --nologo --safe-mode --outdir /tmp/test /tmp/test.docx

I added safe mode and no logo, but that didn't help.

I wonder, if a build with --enable-headless would help. Support for macOS was just added, see 5d4a689293d47c7671315452f6b90a185fe809c0 and other commits in the relation chain.

(In reply to Christian Schmitz from comment #1)
> Call is e.g. 
> 
> /Applications/LibreOffice.app/Contents/MacOS/soffice --convert-to pdf
> --safe-mode --headless --nologo --safe-mode --outdir /tmp/test /tmp/test.docx
> 
> I added safe mode and no logo, but that didn't help.
The above command works fine for me over ssh to localhost, after enabling it in "System Preferences > Sharing > Remote Login" in macOS:

Version: 25.8.3.2 (AARCH64)
Build ID: 8ca8d55c161d602844f5428fa4b58097424e324e
CPU threads: 10; OS: macOS 26.2; UI render: Skia/Metal; VCL: osx
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded

Also, for LibreOfficeDev, built without --enable-headless:

$ instdir/LibreOfficeDev.app/Contents/MacOS/soffice --convert-to pdf --safe-mode --headless --nologo --safe-mode --outdir /tmp/test /tmp/test.docx

Version: 26.8.0.0.alpha0+ (AARCH64)
Build ID: d0265596672d78ad6f3980ff6fb900535aefd11f
CPU threads: 10; OS: macOS 26.2; UI render: Skia/Metal; VCL: osx
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded

I used a very simple docx file with a few characters in it. Is it possible that you share the docx file? The crash can be related to that.

When you try to debug this, you need to run on macOS without GUI logged in.
Like login via ssh remotely to a Mac where nobody is logged in on the GUI.

Did you try that?

The crash happens way before any file is loaded.
The key thing is that some background GUI service is not running, so creating Cocoa controls fails.

(In reply to Christian Schmitz from comment #4)
> When you try to debug this, you need to run on macOS without GUI logged in.
> Like login via ssh remotely to a Mac where nobody is logged in on the GUI.
> 
> Did you try that?
Thanks for describing the problem in more detail. Previously I was testing with a user logged on.

But, now I tested in the scenario that you described, without logging in:

Latest LO 25.8 stable hangs (and not crashes):

Version: 25.8.3.2 (AARCH64)
Build ID: 8ca8d55c161d602844f5428fa4b58097424e324e
CPU threads: 10; OS: macOS 26.2; UI render: Skia/Metal; VCL: osx
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded

Upon logging in, retrying the same command works as expected.

% /Applications/LibreOffice.app/Contents/MacOS/soffice --convert-to pdf --safe-mode --headless --nologo --safe-mode --outdir /tmp/test /tmp/test.docx
soffice[59692:1326884] +[NSXPCSharedListener endpointForReply:withListenerName:replyErrorCode:]: an error occurred while attempting to obtain endpoint for listener 'ClientCallsAuxiliary': Connection interrupted

And it hangs at this point.

But latest LO 26.8 dev master compiled with --headless works fine.

% instdir/LibreOfficeDev.app/Contents/MacOS/soffice --convert-to pdf --safe-mode --headless --nologo --safe-mode --outdir /tmp/test /tmp/test.docx
Fontconfig warning: no <cachedir> elements found. Check configuration.
Fontconfig warning: adding <cachedir>/@.__________________________________________________OOO/var/cache/fontconfig</cachedir>
Fontconfig warning: adding <cachedir prefix="xdg">fontconfig</cachedir>
warn:writerfilter.dmapper:59748:1328413:sw/source/writerfilter/dmapper/DomainMapper_Impl.cxx:1415: this should happen at a section context end
...
warn:legacy.osl:59748:1328413:oox/source/helper/storagebase.cxx:67: StorageBase::StorageBase - missing base input stream
convert /tmp/test.docx as a Writer document -> /private/tmp/test/test.pdf using filter : writer_pdf_Export
warn:vcl.schedule.deinit:59748:1328413:vcl/source/app/scheduler.cxx:181: DeInit task: Timer a: 1 p: 7 desktop::Desktop m_firstRunTimer 3000ms (0x16f853080) (ignored)
warn:vcl.schedule.deinit:59748:1328413:vcl/source/app/scheduler.cxx:202: DeInit active tasks: 1 (ignored: 1)
warn:sal.osl.pipe:59748:1328413:sal/osl/unx/pipe.cxx:354: shutdown() failed: ENOTCONN
warn:sal.osl.pipe:59748:1328420:sal/osl/unx/pipe.cxx:400: accept() failed: ECONNABORTED

I built LO again without --enable-headless to see the difference. The same hang happens in this case:

 % /Applications/LibreOffice.app/Contents/MacOS/soffice --convert-to pdf --safe-mode --headless --nologo --safe-mode --outdir /tmp/test /tmp/test.docx
2026-01-22 06:44:42.009 soffice[51719:1540934] +[NSXPCSharedListener endpointForReply:withListenerName:replyErrorCode:]: an error occurred while attempting to obtain endpoint for listener 'ClientCallsAuxiliary': Connection interrupted

Hang happens here.

You may add the following configuration options, and test yourself with the latest sources:
https://wiki.documentfoundation.org/Development/BuildingOnMac

--enable-headless
--without-system-fontconfig
--without-system-freetype

Therefore, the problem seems to be fixed, and will be available once LibreOffice is shipped with headless mode enabled.

I will ask for adding --enable-headless in the futures builds, and then close this bug report as RESOLVED/FIXED, if there are no objections.

Thanks for testing.
I just tried 25.8.4.2 again.

This still calls 

16  AppKit                        	       0x19c89fd10 -[NSComboBoxCell initPopUpWindow] + 892
17  AppKit                        	       0x19c8f12d4 -[NSComboBoxCell initTextCell:] + 100
18  libvclplug_osxlo.dylib        	       0x1088a7f74 AquaSalInstance::AquaSalInstance() + 440
19  libvclplug_osxlo.dylib        	       0x1088a7d4c create_SalInstance + 248

even if I pass --headless, so maybe this version doesn't do it.

So I may wait for 26.8 being available.
If a nightly build or similar is available, I'd love to try it.