14,5 iMac 27" running on OpenCore after Win10 or Win11 install will not boot into MacOS Sonoma

[Macs4MAVA]

Late 2014 14,5 iMac 27" Running on OpenCore 1.5.0 with Sonoma 14.5 with 32Megs of RAM will not boot into MacOS after a Win10 or Win11 install.

It makes no difference if I use BootCamp to install windows, or manually partition the same drive, and format it to FatEx. The windows installation goes without a hitch for Windows10, yet for Windows11 install I have to disable hardware checks with REGEDIT which is no big deal, but the outcome is the same of not being able boot up again in MacOS.

BootCamp6 drivers install without any problems.

I did remove the small(130gig) NVME drive on the computer, and it purely runs on 2TB Crucial FLASH SSD SATA drive.

I have probably tried this windows install about 10 times in these last few weeks trying all kinds of directions and approaches.

At this very moment, I have installed windows 10, I have not manually rebooted(or turned off the computer), nor have I installed the bootcamp drivers. I am trying to follow the Dortania/OpenCore Wiki page of "Installing Windows in UEFI Mode" . I cannot disable the windows boot picker in the windows text editor (CMD running in administrator mode) per the wiki page.

My understanding is OpenCore does not care if the windows boot picker is installed as OpenCore will find the Windows partition?

FYI, I have tried the making of the manual partition of 200Meg for the OpenCore boot picker, and saving the relevant files(as that occurs automatically) there when OpenCore asks to patch the hard drive, but that does not work either...

I know I'm not the only one with this problem as I found someone else with the identical problem on the SAME iMac on reddit

FYI, this was the first-edition of 5K Retna Fusion Drive 27" iMac's

Any suggestions on which direction to take?

​

 

[LuckyOldMan]

Late 2014 14,5 iMac 27"

A note in advance: it is better to use a large NVMe-SSD as the main storage device instead of a Sata-SSD.

Even if the iMac 2014 only has 2 lanes (like my Mac Mini 2014 has), the NVMe SSD is still faster than a SATA SSD.
This is due to the principle: the SATA SSD does around 500 MB/s - the NVMe SSD can go up to 720 MB/s.
I had to experience this with my iMac 2017.

I have done a few WinOS installations on my Macs and used different methods.

The MP 5.1 requires special precautions (OCLP protection) due to the FW risk in UEFI installation mode.
It is different again with the iMac 18.3 (2017) & Mac mini 7.1 (2014).

The easiest way to install Win was with the iMac 18.3 - it was very easy and almost without any access from my side via Bootcamp. Everything was done in 25 minutes.

With the Mac mini 2014, I divided the internal NVMe-SSD into two partitions. To do this, I used a Monterey install stick to boot so that I could use the disk utility: two partitions, GUID and WinOS/FAT32 for WinOS, and Mac OS Extended (Journaled) for macOS. This will be changed to APFS later.

Then I start with the Win10 installer stick, format in NTFS after the first steps and install Win10 into the selected partition.
I don't use OCLP here yet, but let the Mac boot normally during the installation phases.
When the Win10 installation is complete, I start the corresponding BC driver package until all the yellow question marks in the device manager have been removed.

Then I use a Win11 23H2 ISO, create an installation stick using Rufus (Rufus removes all known hardware restrictions) and start it from the running Win10. All personal data and settings are retained.

If everything works with Win11, I install the desired macOS: with my MM7.1 it stays with Monterey without OCLP.

I suspect that during the WinOS installation, the start files in the EFI of macOS were overwritten by WinOS. Even in the Hackintosh days, with WinOS & macOS on one data carrier, we always installed Windows first and then macOS.

If you have any questions, don't hesitate to ask.

Good luck.

 

[Macs4MAVA]

I have done a few WinOS installations on my Macs and used different methods.

First, Thank you for your reply.

Right about the time you wrote this reply. I figured it out.

The secret is to put the OLCP bootpicker in it's own partition, and disable the efi file as the "Installing Windows in UEFI Mode" overview process explains which are NOT blow blow instructions - there are some holes in the process, but the goal is to disable EFI file...

For the moment it is economics on not using a NVME, but going from Mechanical SATA to a Digital SATA is a 500% change over, yet my SATA of 540 to 700 for a NVME is only 130% more. I'm fine at the moment here.

I will have to try your process on my next intel mac.

I will try something soon; On that little NVME of 130g is High Sierra all ready on it. I will try to put windows 7 with bootcamp if I can with High Sierra. High Sierra is the most this 14,5 iMac will natively update too. I just run old windows industrial software. These old macs make great windows machines.

Thank you for your post,

M...