I’m suspecting you are hitting a certificate issue. Here’s a bit more on it [https://appleinsider.com/articles/19/10/24/if-youve-got-an-old-macos-install-image-it-will-probably-stop-working-today|If you've got an old macOS install image, it will probably stop working today]
Apple released updated installers with new certs. Here’s the collection!
* [https://support.apple.com/en-us/HT206886|How to upgrade to OS X El Capitan]
* [https://support.apple.com/en-us/HT208202|How to upgrade to macOS Sierra]
* [https://support.apple.com/en-us/HT208969|How to upgrade to macOS High Sierra]
* [https://support.apple.com/en-us/HT210190|How to upgrade to macOS Mojave]
In all of these you’ll want to jump to Step 4 and look for the second Blue URL as the first is for Catalina! Apple want to push you to it.
As far as setting up the USB, do make sure you’ve formatted it GUID with a journaled file system (HFS+) before you move over the installer. Some of these are compressed so you’ll need to double click on it twice to launch the installer, then from the menu exit out.
The last issue is you need to run the setup on an older OS and on a system the OS can run on. Apple loves making this hard! So as an example you have a 2018 MacBook Pro you can’t setup El Capitan on it.
I’m suspecting you are hitting a certificate issue. Here’s a bit more on it [https://appleinsider.com/articles/19/10/24/if-youve-got-an-old-macos-install-image-it-will-probably-stop-working-today|If you've got an old macOS install image, it will probably stop working today]
Apple released updated installers with new certs. Here’s the collection!
-
[https://support.apple.com/en-us/HT206886|How to upgrade to OS X El Capitan]
-
-
[https://support.apple.com/en-us/HT208202|How to upgrade to macOS Sierra]
-
-
[https://support.apple.com/en-us/HT208969|How to upgrade to macOS High Sierra]
-
-
[https://support.apple.com/en-us/HT210190|How to upgrade to macOS Mojave]
-
+
* [https://support.apple.com/en-us/HT206886|How to upgrade to OS X El Capitan]
+
* [https://support.apple.com/en-us/HT208202|How to upgrade to macOS Sierra]
+
* [https://support.apple.com/en-us/HT208969|How to upgrade to macOS High Sierra]
+
* [https://support.apple.com/en-us/HT210190|How to upgrade to macOS Mojave]
In all of these you’ll want to jump to Step 4 and look for the second Blue URL as the first is for Catalina! Apple want to push you to it.
As far as setting up the USB, do make sure you’ve formatted it GUID with a journaled file system (HFS+) before you move over the installer. Some of these are compressed so you’ll need to double click on it twice to launch the installer, then from the menu exit out.
The last issue is you need to run the setup on an older OS and on a system the OS can run on. Apple loves making this hard! So as an example you have a 2018 MacBook Pro you can’t setup El Capitan on it.
I’m suspecting you are hitting a certificate issue. Here’s a bit more on it [https://appleinsider.com/articles/19/10/24/if-youve-got-an-old-macos-install-image-it-will-probably-stop-working-today|If you've got an old macOS install image, it will probably stop working today]
Apple released updated installers with new certs. Here’s the collection!
[https://support.apple.com/en-us/HT206886|How to upgrade to OS X El Capitan]
[https://support.apple.com/en-us/HT208202|How to upgrade to macOS Sierra]
[https://support.apple.com/en-us/HT208969|How to upgrade to macOS High Sierra]
[https://support.apple.com/en-us/HT210190|How to upgrade to macOS Mojave]
In all of these you’ll want to jump to Step 4 and look for the second Blue URL as the first is for Catalina! Apple want to push you to it.
As far as setting up the USB, do make sure you’ve formatted it GUID with a journaled file system (HFS+) before you move over the installer. Some of these are compressed so you’ll need to double click on it twice to launch the installer, then from the menu exit out.
The last issue is you need to run the setup on an older OS and on a system the OS can run on. Apple loves making this hard! So as an example you have a 2018 MacBook Pro you can’t setup El Capitan on it.