Q: Blank White screen at startup after installing OSX El Capitan
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Nov 14, 2015 9:34 AMby jeremy_v,Hello Rob,
Thanks for contributing to the Apple Support Communities.
It looks like your iMac shows the Apple logo and then a blank white screen after being upgraded to El Capitan.
In this case, first try safe mode if your Mac doesn't finish starting up.
Starting up in safe mode
Follow these steps to start up into safe mode.
- Start or restart your Mac.
- Immediately after you hear the startup sound, press and hold the Shift key.
- Release the Shift key when you see the Apple logo appear on the screen.
After the Apple logo appears, it might take longer than usual to reach the login screen or your desktop. This is because your Mac performs a directory check of your startup disk as part of safe mode.
To leave safe mode, restart your computer without pressing any keys during startup.
If you don't hear a startup chime after pressing the power key, see what to do if your Mac won't turn on.
The link above has some information on what to try next depending on whether or not your Mac can start up in safe mode:
If an issue doesn't happen in safe mode
If an issue doesn't happen when your Mac is started in safe mode, try restarting again without pressing any keys at startup. If the issue appears to be resolved when you start up normally, it was possibly caused by a cache or a directory issue with your startup disk that safe mode fixed.
If you restart your Mac normally and an issue comes back when you reach your desktop, try disabling any login items that automatically open when you log in.
If your Mac restarts or shuts down in safe mode
If your Mac automatically restarts in safe mode, OS X might have found an issue that it's trying to fix.
Safe mode performs a directory check of your startup disk, similar to what happens when you choose to verify or repair a disk using Disk Utility. If OS X finds an issue, the directory on your startup disk is repaired and your Mac restarts.
If your Mac turns itself off when you start up in safe mode, check the power connection on your Mac to make sure it's plugged in securely at both your Mac and the power outlet. If you're using a MagSafe power adapter, make sure the LED on your power adapter is yellow or green. Then, try starting up in safe mode again.
If your Mac repeatedly restarts or shuts down during safe mode, contact Apple Support, or consult with an Apple Authorized Service Provider or Apple Genius for more help.
Feel free to reply and let us know if this helped, or what happens when you try safe mode.
All the best.
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Nov 14, 2015 10:43 AMby Duane,I had a similar problem happen to my MacBook Pro. I found the thread Reboot fail after installing El Capitan help!! and followed the advice from GSfromNL. This is the post that I used:
1) Open Terminal in /Applications/Utilities
2) Enter "system_profiler SPExtensionsDataType > ~/Desktop/kextList.txt" without the quotes and hit return (this will take a short while to run).
3) There should now be a kextList.txt file on your desktop, open it and press both the "Command" and "F" keys to bring up the find.
4) In the find field insert "Not Signed" Copy the destination to the .kext file to a list for use later. (Click next to cycle through all of them.) Example: /System/Library/Extensions/JMicronATA.kext
5) Browse your drive to /System/Library/Extensions and create a folder by the name Unsupported, move any of the unsigned kext files to the folder Unsupported. Delete the Kexts from their original location.
6) Browse in /Library/Extensions and create again a folder named Unsupported. Look if there are more unsupported Kext's and move them to the folder Unsupported. Delete the Kexts from their original location.
7) Beware that there may be Kext's that are "not signed" that you want to keep because you may need them for programs known and trusted by you, so do not move them to the unsupported folder(s). If you did, no worries, you can always put them back later if there are troubles.
8) Reboot and you should be all set.
