How to troubleshoot LO 6.1.5 launch failure on Windows 10?

Hi,
I recently installed LO 6.1.5 (and subsequently 6.1.6) on Windows 10 x64. The splash screen shows up, the progress bar makes it about half way along then the splash screen disappears and nothing.
Windows Task Manager shows soffice.exe and soffice.bin running but then both disappear.
I can start it in safe mode, but it will NOT start normally.
I’ve disabled OpenGL, via registry settings, but that does not help.
I’ve disabled, rebooted, reinstalled, but the problem persists.
I’ve uninstalled, rebooted, installed 6.1.6, but the problem persists.

I would like to know how to troubleshoot what is causing the launch failure. This question seems to come up frequently, but I have not found any information related to how to determine the root cause of the failure.
Is there some sort of logging of the startup that can be enabled?

I suppose your only option is downloading a daily build, which might output something to console when run.

I did what you suggested, and ran with this:
C:>“Program Files\LibreOfficeDev 6\program\soffice.bin” 2>log.txt
The output contains the single line:
error: Invalid type for value

So something is broken, but how to turn on more logging? The SAL_LOG environment variable doesn’t seem to do anything useful.

Try https://wiki.documentfoundation.org/How_to_get_a_backtrace_with_WinDbg

I did that, this is as far as it gets:

ModLoad: 00007ffbcfe30000 00007ffbcff12000 C:\Windows\System32\CoreMessaging.dll
ntdll!NtTerminateProcess+0x14:
00007ffb`d615fce4 c3 ret

The wiki page has instructions how to produce minidumps. Please create one and attach here, or to a bug report.

Thanks, I opened a bug report here

So the problem turned out to be an issue with OpenCL.
The problem is that you can’t turn off OpenCL from the GUI if the GUI doesn’t open.
I was able to get it started by setting the environment variable SAL_DISABLE_OPENCL=1, then launching soffice.
From there, I was able to disable OpenCL.

Oddly in Linux, OpenCL is disabled by default, and in windows it is enabled by default.

Suggestions for the dev team: have some more output related to OpenCL initialization failures, it was particularly challenging to isolate this as being the issue.