System Information:Item Details PC Model HP EliteDesk 800 G2 SFF CPU Intel Core i5-6500T (Skylake-S, Socket H4 LGA1151) Motherboard HP 8054 (Intel Q170 chipset, KBC Version 05.39) BIOS HP N01 Ver. 02.60 (12/15/2022) RAM 16GB DDR4 (2x8GB): Crucial PC4-21300 + Kingston PC4-17100 iGPU Intel HD Graphics 530 (Skylake-S GT2) Storage 250 GB (ssd) Bootloader OpenCore (latest)
I'm trying to install macOS Sequoia on my HP EliteDesk 800 G2 SFF. I can get to the OpenCore boot picker without any issues, but as soon as I select "Install macOS Sequoia," I immediately get a black screen with a prohibited sign
Problem Summary:
. This happens before the installer even begins — it's not the typical "black screen after the first reboot" issue that some others have encountered.
Boot Sequence + Errors:
- Boot to OpenCore picker → Works
- Select "Install macOS Sequoia" → Fails
- The screen flashes briefly, then I see:
-
Code:
OCS: No schema for LegacyEnable at 2 index, context <NVRAM> 🚫 Prohibited sign OCB: StartImage failed - Aborted
- Photos attached: Images
- OpenCore Picker
- Black screen with prohibited sign
- Boot log with error messages
Diagnosis:
| Symptom | Meaning |
|---|---|
| OCS: No schema for LegacyEnable | Minor warning — leftover/obsolete key from previous OpenCore versions. Harmless. |
| Prohibited Sign | Critical — the installer cannot find a valid environment or missing drivers. |
| OCB: StartImage failed | OpenCore failed to load the macOS installer image properly. Fatal error. |
🛠 Possible Causes + Solutions:
| Area | Action |
|---|---|
| Config.plist | Remove the LegacyEnable key. Validate the config using ProperTree or OpenCore Configurator. |
| SMBIOS | Use a modern SMBIOS (recommend: iMac17,1). |
| SecureBootModel | Set to Default or Disabled under Misc > Security. |
| Kexts | Make sure you're using the latest versions: Lilu, WhateverGreen, VirtualSMC, AppleALC, NVMeFix, etc. |
| UEFI Drivers | Ensure you're using: OpenRuntime.efi, OpenCanopy.efi, and HfsPlus.efi. |
| ACPI | Load basic SSDTs: SSDT-PLUG, SSDT-EC-USBX, SSDT-AWAC (for Skylake timer fix). |
| USB Mapping | Sequoia enforces stricter USB mapping. Build a proper USB map using USBToolBox. |
| Installer USB | Double-check that the USB was built correctly: GPT format, APFS volumes, and a verified installer. |
Extra Notes:
- macOS Sequoia may be more sensitive to outdated settings than older macOS versions like Monterey or Ventura.
- Skylake graphics (Intel HD 530) should work fine, but ensure WhateverGreen.kext is up-to-date.
- If using only iGPU (Intel HD 530), make sure the
AAPL,ig-platform-idis correctly injected for Skylake (0x19120000 or 0x19160000, depending on the specific model). - Some HP desktops may require minor quirks to get USB or Audio functioning properly — these can be addressed after the OS is installed.
Can You Help?
If anyone has advice or suggestions for resolving this issue, I would greatly appreciate it! I’m happy to share my config.plist and additional details about my drive and partition setup to assist with troubleshooting.Thanks in advance for your help!
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