How to sign into iCloud after installing Yosemite on 2014 iMac

If you have other trusted devices the code should automatically be sent to them. If not, you can request a code be sent by text or by a phone call to your trusted phone number. See instructions in Get a verification code and sign in with two-factor authentication - Apple Support

Then append the code to your password.

If you are trying to upgrade from Yosemite to something newer, you may need to make an intermediate upgrade to Sierra.

How to download and install macOS - Apple Support

Sierra is the highest version of macOS for which the installer is available in .DMG form – and the lowest version of macOS that's now compatible with iCloud. Once you upgrade it to it, maybe you wlll have better luck with signing into iCloud, and accessing the App Store to upgrade further.

You would probably want to stop either at

• High Sierra – if you have 32-bit applications that you want to keep using, or
• Big Sur – if you want to be able to run current versions of Firefox, LibreOffice, etc.

erickdobrasil wrote:

Except I cannot get my 2014 Imac to boot from what appears to be a perfectly valid usb 3.0 samsung dongle which was created on my mac mini with the createinstallmefia command. The dongle was formatted with extended journaled filesystem and GUID. When I boot Imac and hold down the Option key on a wired keyboard I never get any boot device menu…it just boots into Yosemite from the SSD I installed inside the Imac.

Make sure to wait until you hear the startup chime before you press any keys. Immediately after hearing the startup chime, press the Option key. Sometimes a Mac will not recognize the special startup keys if they are pressed to early or too late.

Even if the USB stick is not bootable, you should still be able to access the Apple boot picker menu when Option booting. Maybe try pressing the other Option key on the keyboard instead just in case it has a problem.

You can also try a PRAM Reset (hold for at least three chimes if possible).

I also tried using Mist to download Big Sur but no luck either booting it. Diskutil on the Imac shows an EFI partition on the dongle but not able to manually mount the EFI…it is not recognized. I am reaching a high level of frustration 😂

The Disk Utility GUI hides the EFI partition from view since the average user has no need to access it. I'm not even certain Apple even still uses it for booting with later versions of macOS.

Another option is to download the macOS 10.11 El Capitan installer. This installer is available outside of the App Store and can be downloaded with any computer that can access the Internet. Just transfer the DMG from one computer to the iMac running Yosemite, just make sure to follow the multiple steps to extract the real full installer after which you will need to manually launch the full installer from the Applications folder. See the following Apple article for details:

How to download and install macOS - Apple Support

Once you have El Capitan installed, then you should theoretically be able to access the App Store to download a later version of macOS (use the links in the above Apple article).

You can install something much newer than Yosemite. Refer to this specific step in How to reinstall macOS - Apple Support:

• If you used Option-Command-R to start up from Internet Recovery, you might get the latest macOS that is compatible with your Mac.

That ought to be Big Sur.

Make sure to wait until you hear the startup chime before you press any keys. Immediately after hearing the startup chime, press the Option key. Sometimes a Mac will not recognize the special startup keys if they are pressed to early or too late.

No such conniptions are required. Since different Macs have different boot times I just rest a pocketknife on an Option key while I go do something else. Startup Manager will be waiting.

Wired (USB) or wireless makes no difference, though they are all Apple keyboards.

Startup Manager will appear even if a Mac cannot find any boot device. If those icons of bootable devices do not appear, either something is wrong with OP's keyboard or a firmware password has been set (which prevents booting from anything other than the previously designated startup disk):

• Some key combinations don't work when your Mac is using a firmware password. Turn off the firmware password first.

John Galt wrote:

Make sure to wait until you hear the startup chime before you press any keys. Immediately after hearing the startup chime, press the Option key. Sometimes a Mac will not recognize the special startup keys if they are pressed to early or too late.

No such conniptions are required. Since different Macs have different boot times I just rest a pocketknife on an Option key while I go do something else. Startup Manager will be waiting.

I've personally had multiple Macs (desktops & laptops) not boot if the special startup keys are held too early or too late. It usually occurs most often on the USB-C Macs. It is not consistent. Sometimes I can hold the key early and a USB-C Mac will recognize it, other times it may even prevent the Mac from even booting until the key is released.

Startup Manager will appear even if a Mac cannot find any boot device. If those icons of bootable devices do not appear, either something is wrong with OP's keyboard or a firmware password has been set (which prevents booting from anything other than the previously designated startup disk):

None of the affected Macs where I've seen the issue with timing the key presses had a Firmware Password. Only the timing of the key press was needed to access the various boot mode options.

That is how it always worked on the older Macs, but that is not always the case especially with the USB-C Macs. The USB-C Macs have a lot of odd quirks.

I work on a lot of Macs for my organization which is probably why I have seen this occur so much. I'm always using an Apple wired keyboard or the laptop's built-in keyboard. I've never noticed any pattern, but I also never looked for one since I know how to work around the issue when it occurs. I just chalk it up to a USB-C Macs quirks (they do have a lot of quirks).

Might that be related to your inability to boot Recovery?