Bootable Catalina Flash Drive will not start up iMac

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Level 1

19 points

Bootable Catalina Flash Drive will not start up iMac

I followed the instructions from the link below for creating a bootable flash drive for Catalina with Terminal.

https://support.apple.com/sl-si/HT201372

The screen shot below of Terminal of the completed task indicates it was successful.

The instructions for "Use the bootable installer" in the link (creating a bootable disk) above were also followed. The volume containing the bootable installer in step 4 of the process does not show up. From the link below my 2017 iMac, does not have the External Boot setting in Startup Security Utility also mentioned in step 4.

https://support.apple.com/en-us/HT208862

Why isn't my bootable installer working? Any advice would be appreciated.

Thanks,

Charlie

Posted on Jan 10, 2022 10:48 PM

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Answer 1

Owl-53

Level 10

102,871 points

Jan 11, 2022 2:49 AM in response to Varoop13

How is the Bootable Installer USB Drive to the computer. Best results are Directly to the computer.

Suggest shutdown the computer completely and disconnect ALL Other External Drives except the Bootable Installer Drive.

Restart the computer and immediately hold the Option key. This should offer the Startup Manager. It should present either the Bootable Installer Drive or the Internal Drive as options. Choose the Bootable Installer Drive.

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Answer 2

Varoop13 Author

Level 1

19 points

Jan 11, 2022 7:26 PM in response to TheLittles

Thank you TheLittles. Resetting the SMC allowed the Bootable Catalina Flash Drive to start up. I did not attempt the NVRAM step.

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Answer 3

TheLittles

Level 10

203,109 points

Jan 11, 2022 7:33 PM in response to Varoop13

Varoop13 Said:

"Bootable Catalina Flash Drive will not start up iMac: Thank you TheLittles. Resetting the SMC allowed the Bootable Catalina Flash Drive to start up. I did not attempt the NVRAM step."

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You are welcome.

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Answer 4

TheLittles

Level 10

203,109 points

Jan 10, 2022 11:28 PM in response to Varoop13

Varoop13 Said:

"Bootable Catalina Flash Drive will not start up iMac: The volume containing the bootable installer in step 4 of the process does not show up. From the link below my 2017 iMac,[...]"

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For a 2017 iMac, try the following...

Reset the SMC and your NVRAM:

If not recognized, then note that sometimes when changes are made to the system(i.e. updates), system configurations (i.e. for USB) become manipulated, technically. So, reset the SMC and NVRAM.

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Answer 5

Varoop13 Author

Level 1

19 points

Jan 11, 2022 7:28 PM in response to Owl-53

Thanks for your input, P. Phillips. I had tried all your suggestions before posting my comment.

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Bootable Catalina Flash Drive will not start up iMac

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