Failed Sequoia install late 2013 iMac

[Les_Garten]

I have a late 2013 iMac that was running Monterey.

I setup USB drive to install Sequoia. Install went fine.

sequoia came up and I installed the post install root patches and after boot I get the prohibited circle with the slash and in the upper left corner it says OC: Boot failed - Aborted OCB: StartImage failed

I tried several times to boot with the install usb and nothing helped.

booted into recovery and formatted the internal SSD to do a clean install but cannot get past the prohibited circle screen.

This machine has worked fine for the last few years on Monterey after installing 32gb RAM, a 1TB NVME drive and a 2TB SATA SSD. Really want 6to get it back working with Sequoia

I have access to a M4 Mac Mini where I made a new Installer USB. I boot up with it and try to boot the EFI parttion and it just keeps giving me the prohibited screen.

 

[Barnclos]

Two things:
- it is relatively early days for OCLP and Sequoia, could you get by with Sonoma (or Ventura) until OCLP/Sequoia has had time to do some bug fixes?
- OCLP installers are machine specific, so you’ll need to specify your old machine when creating an installer on your M4 mini (I’ve never had to do this, so can’t give details but I’m sure it’s googleable).

 

[headlessmike]

I have a late 2013 iMac that was running Monterey.

I setup USB drive to install Sequoia. Install went fine.

sequoia came up and I installed the post install root patches and after boot I get the prohibited circle with the slash and in the upper left corner it says OC: Boot failed - Aborted OCB: StartImage failed

I tried several times to boot with the install usb and nothing helped.

booted into recovery and formatted the internal SSD to do a clean install but cannot get past the prohibited circle screen.

This machine has worked fine for the last few years on Monterey after installing 32gb RAM, a 1TB NVME drive and a 2TB SATA SSD. Really want 6to get it back working with Sequoia

I have access to a M4 Mac Mini where I made a new Installer USB. I boot up with it and try to boot the EFI parttion and it just keeps giving me the prohibited screen.

To me it sounds like you are trying to boot Sequoia without having OpenCore (OC) activated at boot.

Did you install OpenCore (using OCLP) to your boot drive? The OCLP installer setup will install OC to the USB drive's EFI partition, which you select when booting the computer after holding down shift when powering it on. After the installation you'll probably want to install OC to your SSD instead (so that you can boot the machine into an unsupported macOS without have the USB drive plugged in) in addition to installing the root patches. Once you have OC installed on the internal drive you will have to hold shift again while powering it on to select the EFI partition on your internal SSD. That should then take you to the OC boot picker where you can select the OS (or installer) you want to boot. If you already have OC installed on your internal drive you will not need to use the USB drive's EFI partition either.

As Barnclos points out it is also important to verify that you chose the correct hardware when setting up the USB installer from your M4 Mac. Depending on your specific model of iMac it should have an iMac14,x identifier where x is 1, 2, or 3.

 

[Les_Garten]

I'm not sure why this started coming up. It was after I had a Stable Monterey install with Open Core for the last few years. I tried to install sequoia and it did that. I got Monterey back on there and am now having different OCLP issues, so I'll take my issues to a different thread for that. Thanx for all the input here.