iMac 2009 shows no entry sign after OCLP Monterey

[Pat Hughes]

I had Monterey up and running fine yesterday all day on my 27" late 2009 iMac. Everything worked fine and did photo and video editing with it. Last night I shut it down and this morning I saw the prohibit sign on a grey screen and a moment later it shuts down. Repeated attempt to turn it on with same results. I am using an external SSD USB which I installed the Monterey on. The original spinning HD is inside the iMac running High Sierra that I used to inatall Monterey on the SSD. Funny thing is, yesterday I restarted with Monterey several times without issue while holding the option key and choosing the SSD. I know the unit is old but why all of a sudden this morning it does that and how can I correct it. I will accept Catalina if need be as I would like to get a few programs that do not run on High Sierra. Once working fine with Catalina, Big Sur or Monterey I will transfer the SSD internally.

 

[Bigwaff]

So booting while holding down the "option" key does not bring you to the boot picker? If it does, pick EFI Boot first, then pick your macOS w/OpenCore boot disk.

 

[Pat Hughes]

Thanks, I tried that but but does not show the EFI just shows the external orange SSD where Monterey is. When I choose it the screen goes to no entry sign. Perhaps it needs that EFI and may be a way to install it somehow. Yesterday I saw that EFI next to the SSD. Also when I am booted in High Sierra, the startup disc on system preferences only shows the High Sierra.

 

[Pat Hughes]

OK, got it figured out and now is working properly. I Started it up in High Sierra and hit the Open Core application. From there I just chose to apply the OC patcher like I did when I installed Monterey , making sure that I chose the external SSD. That's all. No need to re-install the OS over again. I shut down, started with option pressed and the EFI showed up right next to the SSD. Why did it just disappear this morning ? At least now I know in case it happens again.

 

[specialstyle]

OK, got it figured out and now is working properly. I Started it up in High Sierra and hit the Open Core application. From there I just chose to apply the OC patcher like I did when I installed Monterey , making sure that I chose the external SSD. That's all. No need to re-install the OS over again. I shut down, started with option pressed and the EFI showed up right next to the SSD. Why did it just disappear this morning ? At least now I know in case it happens again.

Computers can be weird! You can also make yourself a USB-installer just in case you need to get to disk utility in the future -- especially when that internal drive stops working -- at least you'll be able to pivot from that back into the machine.

 

[Nguyen Duc Hieu]

OK, got it figured out and now is working properly. I Started it up in High Sierra and hit the Open Core application. From there I just chose to apply the OC patcher like I did when I installed Monterey , making sure that I chose the external SSD. That's all. No need to re-install the OS over again. I shut down, started with option pressed and the EFI showed up right next to the SSD. Why did it just disappear this morning ? At least now I know in case it happens again.

You have messed up with the booting order. That's why.
When you install Monterey on the external SSD, you now have 2 EFI volumes.
When booting up, the iMac will search for EFI volume on the internal HDD first. USB devices are external and on the second boot sequence.
When you boot and hold Option, the iMac lets you choose which EFI volume to boot from.
When installing OCLP, something in the internal EFI volume was modified, so if you don't press and hold Option upon power-up, the iMac found no working EFI volume => No boot device found.

Solution:
1. Boot to Monterey on the external devices, run OCLP, then root patch. (Done)
2. Wipe out the internal HDD for data storage only. (not reformat, delete the whole disk, then create new volume again.)
3. Now buy a SATA cable; a SATA power splitting cable and move the SSD inside. 2009 iMac is easy to work with.

 

[Pat Hughes]

Thanks, just installed the SSD with Monterey inside the iMac. Took out the original spinner with h sierra out. Works great. I was attempting the same upgrade to Monterey on my friend's 2012 iMac using a 1TB SSD external USB (APFS formatted ). The Monterey installer in the USB stick stops installing to the SSD at exactly 15 minute mark (halfway) into the progress. I repeated to re-install many times but the same spot it stops. I was patient and gave it over 3 hours wait before I shut it down and started over. I am using the latest OCLP version 1.5.0.

Suggestions, anyone

 

[Nguyen Duc Hieu]

Thanks, just installed the SSD with Monterey inside the iMac. Took out the original spinner with h sierra out. Works great. I was attempting the same upgrade to Monterey on my friend's 2012 iMac using a 1TB SSD external USB (APFS formatted ). The Monterey installer in the USB stick stops installing to the SSD at exactly 15 minute mark (halfway) into the progress. I repeated to re-install many times but the same spot it stops. I was patient and gave it over 3 hours wait before I shut it down and started over. I am using the latest OCLP version 1.5.0.

Suggestions, anyone

I did my second Monterey ugprading as follows, after 1 whole night waiting for Monterey to finalize the set-up and boot to Desktop screen (iMac 2009)
1. Clone the internal Monterey SSD in iMac 2009 to an external SSD.
2. Run OCLP to generate compatible EFI to the new iMac (mine was 2011) and appropriate GPU set-up. Then overwrite the EFI volume on the external SSD
3. Take the External SSD to the new iMac to boot.
After confirming it works well, move in inside the iMac.