unable to install catalina from bootable external drive

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unable to install catalina from bootable external drive

I have an Macbook Air early 2015 and I'm trying to finish doing a full factory reset using a bootable external drive. And it's not working

I started down this path because the computer on startup would give me a file icon with a question mark in it, I couldn't boot to recovery mode, and while I could fire it up after resetting NVRAM, if I shut down and restarted I'd have the same problem as before.

It won't recover from the internet.

So to start fresh, I reformatted the external drive to GUID partition map and Mac OS Extended (Journaled) format; the external now has a Catalina installer (only) on it (which is what I want to install on the computer).

Now, when I plug the external into the computer and start it while holding down the option key, I only get one available startup disk. If I select it and press enter, I can get to the recovery menu. But when I choose to install catalina, the machine decides it wants to install catalina on the bootable drive! It won't do that because it says the drive is locked, but it also won't use the bootable drive to install the OS on its own internal drive.

Any suggestions?

Thank you!!!

Posted on Jan 13, 2025 11:19 AM

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Answer 1

Top-ranking reply

D.I. Johnson

Level 8

38,103 points

Jan 13, 2025 2:11 PM in response to brownriver8

When you reformatted the internal drive from recovery mode, you will have needed to erase the drive device, not just a volume which would have been indented below the device. The device will have a name something like "Apple xxxxxx... Media".

Please reboot in recovery and launch Disk Utility. In Disk Utility's menu bar at the top of the screen click View > Show All Devices. You should now see the device with the name ending with Media. Click and erase the device.

If you plan to reinstall macOS Catalina, then when you erase the device, select the GUID Partition Map for Scheme, Select APFS for Format and then name the device "Macintosh HD". Click Erase and let Disk Utility do its thing.

With that done properly you should now be able to reinstall macOS on the internal drive.

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Answer 2

Jan 13, 2025 5:47 PM in response to brownriver8

You're welcome.

Apple Disk Image is not the internal drive. You may ignore that and MacOS Base System.

If no other drive device is presented to you, usually listed above the Apple Disk Image, then it may very well be that the internal drive has failed and is not communicating with the OS.

While booted in recovery mode or from your bootable usb drive, please open the Terminal app and type this:

diskutil list then press enter. You should see something fairly similar to this:

Please post your result.

Please also submit a screen shots of the whole Disk Utility window and what you are seeing. Make sure you have selected View > Show All Devices from the Disk Utility menu bar. Select the topmost device, probably named "Apple xxx... Media". Also show a pic of any container or volume listed below it.

Please see: View all devices or only volumes in Disk Utility on Mac - Apple Support

Meanwhile, for your reading pleasure:

How to reinstall macOS - Apple Support

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Answer 3

brownriver8 Author

Level 1

5 points

Jan 13, 2025 5:27 PM in response to D.I. Johnson

Thank you!

Still doesn't solve the issue, though.

I'm pretty sure I did erase the drive device, but even if not, I don't have access to the native drive any longer. I can reboot in recovery mode, but only with the bootable external plugged in. From there I can get to disk utility, and see both the external and the onboard drive--which is now called "Apple disk image, with the subunit called "MacOS Base System" But I'm not given the option of erasing that. It looks like I can eject it, but if I click on the eject symbol it tells me it failed to do that because the drive is currently in use.

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unable to install catalina from bootable external drive

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