I use a MacBook Pro I7 of 2012 with 8 Giga Ram and Mac OS El Capitan.
About 10 days ago, I had a hard crash whilst editing a photo on Lightroom 6. It was impossible to start again the computer. I had to reinstall El Capitan from scratch but lost a few datas in the operation. After a proper save of all datas on an external drive, I tried to use again Lightroom 6, and again systematically had crashes. This time I was more lucky as I managed to start the system without reinstalling the OS. Then, I thought I may solve the issue by upgrading the OS to Mac OS SIERRA. This was apparently not a good ideas as it crashed seconds after lauching LR6. I then decided to uninstall / reinstall LR6. Again probably not a good idea as I can not install from the DVD. It blocks and I get a message "download support Advisor". I tried to do it but cannot find any help corresponding to my problem.
A bit frustrating I must confess.
Brgds / PhilippeZ
Please use the below download for Lightroom 6 also, as soon as you launch the Lightroom 6 after install please turn off the GPU from the Lightroom preferences.