I have Lightroom 6 version 6 purchased in August 2018 installed on my Apple Mac with macOS Mojave Version 10.14.6; I have declined upgrades to higher OS versions including declining the most recent for macOS Monterey; however Lightroom now crashes on startup. "Lightroom quit unexpectedly" followed by several pages of Problem Details and System Configuration. It was working just fine, but now it won't start up. Screenshot of first page of 16 of Problem Details and System Configuration attached.
A late reply, but there have been other reports about this. There is a newer version of LR 6 available, LR 6.14. Others have recently reported that updating to LR 6.14 fixed crashing-on-startup problems. Try installing the much newer 6.14, which you can download following these instructions: