iMac Won’t see external startup

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Level 1

135 points

iMac Won’t see external startup

I have a 2017 iMac that is getting stalled on start up and I’ve tried all the suggested options. I had a feeling it was an internal drive so I bought an external drive formatted it correctly and when I hold the option key during start up, the Mac only gives me the option of its internal drive, which I think is having a problem. I know the external drive is formatted correctly as a start of a drive because my wife’s MacBook sees it fine. I can’t understand why it does not see this drive any help appreciate it.

iMac 27″ 5K, macOS 13.2

Posted on May 12, 2023 2:53 PM

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Answer 1

Old Toad

Level 10

218,184 points

May 12, 2023 3:30 PM in response to Tom Hartman1

What is on the eternal drive? Did you install the system or clone your current internal drive to it? I have a 207 27" iMac and boot regularly from external dries with various systems on it.

Try cloning your current boot drive to the external SSD as follows:

1 - make sure you have a full and current backup of your drive.

2 - erase the external SSD and format it to ASPF with Disk Utility.

3 - using Carbon Copy Cloner drag the internal drive into the Source bin and the external SSD into the Destination bin:

3 - Control (right) - click on the Destination bin and select Legacy Bootable Backup Assistant from the contextual menu:

4 - then click on Start.

When done select the external SSD as the startup drive in the System/General/Startup Disk settings pane and reboot.

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Answer 2

Tom Hartman1 Author

Level 1

135 points

May 12, 2023 3:49 PM in response to Old Toad

The iMac will not start up so there is no getting to carbon copy, cloner, etc. that’s why I bought an external and formatted it using my wife’s MacBook Pro which sees the drive just fine.

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iMac Won’t see external startup

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