MacBook Pro REQUIRES Network connection to install/update via USB install drive?

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Level 4

1,094 points

MacBook Pro REQUIRES Network connection to install/update via USB install drive?

System: MacBook Pro (15-inch, 2018)

OS: 10.14, 10.15, 11.0.1

I have several USB Install drives (10.14, 10.15, 11.0.1) I use to wipe/refresh systems in a work environment.

When attempting to update the above-referenced MBP, I select to boot from my USB install drive as usual, but the system then brings me to the spinning-globe network/WiFi screen and there is no option to continue.

I am in an environment without internet connectivity, hence my use of USB drives to do clean installs.

Please tell me I'm missing a step and Apple hasn't killed off-line installs. Please.

peace

~( ):>

MacBook Pro with Touch Bar

Posted on Dec 24, 2020 4:02 AM

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Answer 1

liquidmice Author

Level 4

1,094 points

Dec 24, 2020 10:34 PM in response to liquidmice

I'm going to answer my own question here so the answer is available. Also, I'm stupid and I already knew this in theory.

Apple Security enhancements on T2 Chip Macs block booting from external media by default. In order to change the setting, you need:

To have any firmware and/or system passwords
To boot into Recovery Mode
Go to Utilities-->Startup Security Utility
Change the default setting from the Allowed Boot Media section from "Disallow booting from external or removable media" to "Allow booting from external or removable media."

Then, you can reboot to the external USB drive, wipe, reinstall, and get yourself a true clean install of OS X.

peace

~( ):>

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Answer 2

VikingOSX

Level 10

123,120 points

Dec 24, 2020 4:13 AM in response to liquidmice

Test it in an environment where you have a network connection, and if the installation proceeds normally, you will have your answer. I never perform a clean install, update, or upgrade without a wired or wireless connection, and in the case of portables, connected to a power source, and this has been my practice for years.

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Answer 3

liquidmice Author

Level 4

1,094 points

Dec 24, 2020 5:21 AM in response to VikingOSX

Unfortunately I'm in a technical environment, one where I cannot do that. At least, not at this time. Was hoping to find a workaround. Isolating systems from network connectivity has been my practice for the last 15 years, so we're coming from different worlds! Thanks for the suggestion though and happy holidays.

~( ):>

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MacBook Pro REQUIRES Network connection to install/update via USB install drive?

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