Obfusco
Level 1 (8 points)
Mac OS X

Q: El Capitan update, no longer boots from external HD

Mac mini quad core i7, 2.3 GHz. I was running 10.8.5 on Seagate external hard drive as my Startup Disk. I had attempted to update to El Capitan 10.11.6, via the App Store. Had trouble a time or two. Tried again and it appeared to work. After the update process and the restart, it booted from the internal disk still running 10.8.5. I clicked on System Preferences and chose the external as the Startup Disk. It stated, "Your computer will start up using OS X, 10.11.6 on "external."" When it restarted it came up on the internal disk. Tried restarting and holding the option key. It doesn't show the external disk as an option. It shows the internal, recovery and EFI Boot. The external does show on the Desktop of the internal after reboot. All the files on the external are accessible. Several of the Apps in the Application folder display the "no symbol" or circle backslash. I reset the NVRAM. I also ran Disk Utility on both drives, it said all was well.Prior to using the drive, I formatted it Extended (Journaled). Not using software from Seagate.

Mac mini, OS X Mountain Lion (10.8.5)

Posted on Sep 3, 2016 10:04 PM

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Obfusco

Q: El Capitan update, no longer boots from external HD

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  • by JayB.,

    JayB. JayB. Sep 4, 2016 2:39 PM in response to Obfusco
    Community Specialists
    Sep 4, 2016 2:39 PM in response to Obfusco

    Hi Obfusco,

    I understand that you installed OS X El Capitan on your external HD and your Mac is not recognizing the external drive as a startup disk.  Great way to perform the NVRAM reset and boot up to the startup manager to try and resolve. If that did not work, it may be necessary to reinstall El Capitan on the external drive to repair OS X on that drive. It would be best to erase the drive and then reinstall OS X if you have the data on this external drive saved elsewhere already. Since you've done it a few times before, I'm pretty sure you've got it under control. But, you can use this link for further assistance if needed.

     

    How to reinstall OS X

     

    Thanks for using Apple Support Communities to post your question. Have a nice day. 

  • by Obfusco,

    Obfusco Obfusco Sep 4, 2016 3:06 PM in response to JayB.
    Level 1 (8 points)
    Mac OS X
    Sep 4, 2016 3:06 PM in response to JayB.

    Hey JayB.,

    I was hoping not to reinstall or erase and reinstall. I figured there was a fix I missed. This is the first time I have had an issue with an update. There are worse things in life. I do have a TM back-up. I might reinstall without TM and see if that works. I wanted to try El Capitan. Not so sure now.