Updating OS on bootable external SSD question

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Updating OS on bootable external SSD question

I have an old bootable drive, it is running Yosemite 10.10.1.

Through App Store, it wants to update to 10.10.5. I'm eventually going to take it up to Mojave.

When I said to update, it said a restart was needed so I stopped it because if I restart, my internal HD will come back on (which is running Mojave), as that is set as the startup disk, and I don't want to mess with that.

Should I first set my external HD as the startup disk, to overcome this problem? Or doesn't it make any difference, and it won't install Yosemite over the top of Mojave anyway, and will wait until I next boot into the external to install Yosemite update?

If I can update direct to Mojave, where would I go to get that installer?

Thanks.

Posted on Apr 19, 2022 9:04 AM

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Answer 1

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HWTech

Level 9

69,386 points

Apr 19, 2022 9:45 AM in response to Kathykate

If nothing was copied by the installer, then sure you can set the default Startup Disk, but it may not matter since I've had a lot of Macs reboot to the internal drive during the restart phase while installing to the external drive. It won't hurt your internal drive. Just reboot and do an Option Boot to select the orange icon for the external boot drive to continue the macOS install of the external drive.

You can find links to various macOS installers as well as optional instructions for creating a bootable macOS USB installer in this Apple article (sometimes it may be necessary to upgrade first to 10.11 or 10.13, but you should be able to go directly to 10.14):

How to create a bootable installer for macOS - Apple Support

Make sure to have a good backup before attempting to upgrade macOS just in case something goes wrong. I highly recommend you create the bootable macOS USB installer so you may have more options if something does go wrong although you do have your bootable internal drive to fall back on.

You should always have frequent and regular backups of your computer and all external media (including the cloud) which contains important & unique data.

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Answer 2

Kathykate Author

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248 points

Apr 23, 2022 12:22 AM in response to Kathykate

Thank you for your reply. All good information. I haven't done it yet, but today is the day (as I am getting my backup drive, so once I've backed it up I can go ahead. And I will make the backup bootable, so don't think I will need a bootable mac OS installer drive?).

I was being cautious because I was having trouble doing a boot using Option key, it wasn't working for me, I never got the option to select a different drive - well, it worked a few times, but then stopped working. So I followed some steps to reset PRAM and now it works fine again. So I probably will set the drive I'm installing onto to temporarily be my startup disk, just to be on the safe side.

Once other question I have - I've found and downloaded the Mojave installer, it's not very big, can I put that on a pen drive to use on other machines?

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Answer 3

HWTech

Level 9

69,386 points

Apr 23, 2022 12:39 PM in response to Kathykate

Kathykate wrote:

Once other question I have - I've found and downloaded the Mojave installer, it's not very big, can I put that on a pen drive to use on other machines?

You can transfer the installer file to any media, but it won't be usable unless you can boot into macOS in order to run the installer app. If you used the instructions in my previous post to create a bootable macOS USB installer (requires using the Terminal commands), then you can use the USB installer on any Mac which is compatible with the OS installer you created (for macOS Mojave that would be most Macs from 2012 to 2018). This assumes that you downloaded the macOS installer direct from the Apple App Store using the link in my previous post. It is very risky downloading the installer from anywhere else but Apple.

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Updating OS on bootable external SSD question

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