How to Use OS X Boot Options to Troubleshoot Your Mac
Feb 01, 2017 · OS X El Capitan is the twelfth major release of OS X for Mac computers. It was released on September 30, 2015. Some users have reported an issue where Mac refuses to finish booting after updating to OS X EL Capitan. If your Mac will not start up, stalls on a gray screen with an Apple logo, here is how you troubleshoot. Mar 12, 2017 · A Mac can't boot from a MBR disk and needs a GPT partition scheme to be able to boot from; "And to function as a startup disk, it needs to be using a GUID partition map." from support page: How to set up and use an external Mac startup disk - Apple Support Jun 28, 2020 · For example, Nvidia GTX 750 Ti can't work with Mac OS X earlier than Yosemite. After such a software update, Mac is not worknig, or the Mac or MacBook gets stuck on a loading bar after update. Once the third-party software and hardware on your Mac won't work with the latest macOS, your Mac won't turn on. When you start up in Safe Mode your Mac will not load startup items and some software. The mode also performs a check of your startup disk so it should be able to alert you to problems. Read about
How to Stop Mac Apps From Launching at Startup | PCMag
Fix Mac OS X El Capitan will not start up after update Feb 01, 2017
Step #5: Release the key and let the Mac usually start. Solution 6: Restart Mac Safe Mode. Safe mode is a foolproof solution if your Mac won’t start or Mac crashes continuously. It limits some of the apps while startup and Mac feel little reliable and start without carrying much load at the startup.
Aug 12, 2017 · What I did to fix Problem #12 was to use the High Sierra file from this page. During setup I selected transfer from other mac. My original VMware hard disk file that was not booting was still connect, and I transferred all my settings to the new Mac OS High Sierra file that is on the page here. That file is formatted as Mac Os Journal Extended.