Fixing 'Permission Denied' Upgrade Errors on 2017 5K iMac (macOS Sequoia OCLP)

Tutorial: Resolving 'Permission Denied' Installer Errors in OCLP Sequoia

If you are encountering a "Permission Denied" error when trying to upgrade your 2017 27" 5K iMac (iMac18,3) to macOS Sequoia using OCLP, here is how to resolve this installation block:

1. Re-enable System Integrity Protection (SIP)

Turning SIP off completely can actually cause permission verification errors during macOS installation, as the installer script expects valid security handshakes. Turn SIP back on to standard OCLP recommended defaults:

1. Open the OCLP app.
2. Go to Settings -> Security Settings.
3. Set SIP to the default recommended state (do not manually disable it).
4. Build and install OpenCore, and restart your Mac.

2. Check the Fusion Drive & Disk Permissions

Your iMac has a Fusion Drive (SSD + HDD combo). Sequoia's APFS driver is highly strict about disk health and layout permissions:

1. Reboot in Recovery Mode (hold Cmd+R at boot).
2. Open Disk Utility, select your main drive volume group, and run First Aid on both the physical drives and the container.
3. If permissions are corrupted, first aid will repair the APFS structure.

3. Use the USB Installer Method (Instead of In-App Upgrade)

If the upgrade still fails within the macOS environment:

• Use OCLP to download the Sequoia installer and flash it to a USB drive.
• Install OpenCore EFI to the USB drive.
• Boot from the USB drive (hold Option), select EFI Boot, then choose Install macOS Sequoia from the boot picker. This bypasses permission blocks of your active Ventura environment.