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Help: macOS Sequoia - Installation Problem (Prohibited Sign 🚫 During Installer Boot)

Hurling7051

New member
Joined
Apr 24, 2025
Messages
13
Motherboard
GIGABYTE H110M-S2-CF (BIOS F27b - 07/31/2024)
CPU
Intel Core i3-7100
Graphics
Intel HD Graphics 630
OS X/macOS
15.x
Bootloader
  1. OpenCore (UEFI)
Mac
  1. iMac
Mobile Phone
  1. Android
  2. iOS
  • 🖥️ System Information:

    ItemDetails
    PC ModelHP EliteDesk 800 G2 SFF
    CPUIntel Core i5-6500T (Skylake-S, Socket H4 LGA1151)
    MotherboardHP 8054 (Intel Q170 chipset, KBC Version 05.39)
    BIOSHP N01 Ver. 02.60 (12/15/2022)
    RAM16GB DDR4 (2x8GB): Crucial PC4-21300 + Kingston PC4-17100
    iGPUIntel HD Graphics 530 (Skylake-S GT2)
    Storage250 GB (ssd)
    BootloaderOpenCore (latest)

    ❗ Problem Summary:

    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 🚫. 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:


    1. Boot to OpenCore picker → Works ✅

    2. 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
  1. Photos attached: Images
    • OpenCore Picker
    • Black screen with prohibited sign
    • Boot log with error messages

🔎 Diagnosis:

SymptomMeaning
OCS: No schema for LegacyEnableMinor warning — leftover/obsolete key from previous OpenCore versions. Harmless.
🚫 Prohibited SignCritical — the installer cannot find a valid environment or missing drivers.
OCB: StartImage failedOpenCore failed to load the macOS installer image properly. Fatal error.

🛠 Possible Causes + Solutions:

AreaAction
Config.plistRemove the LegacyEnable key. Validate the config using ProperTree or OpenCore Configurator.
SMBIOSUse a modern SMBIOS (recommend: iMac17,1).
SecureBootModelSet to Default or Disabled under Misc > Security.
KextsMake sure you're using the latest versions: Lilu, WhateverGreen, VirtualSMC, AppleALC, NVMeFix, etc.
UEFI DriversEnsure you're using: OpenRuntime.efi, OpenCanopy.efi, and HfsPlus.efi.
ACPILoad basic SSDTs: SSDT-PLUG, SSDT-EC-USBX, SSDT-AWAC (for Skylake timer fix).
USB MappingSequoia enforces stricter USB mapping. Build a proper USB map using USBToolBox.
Installer USBDouble-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-id is 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! 🙏
Screenshot_2025-04-25_11-50-34.png
 

Attachments

Last edited:
  • 🖥️ System Information:

    ItemDetails
    PC ModelHP EliteDesk 800 G2 SFF
    CPUIntel Core i5-6500T (Skylake-S, Socket H4 LGA1151)
    MotherboardHP 8054 (Intel Q170 chipset, KBC Version 05.39)
    BIOSHP N01 Ver. 02.60 (12/15/2022)
    RAM16GB DDR4 (2x8GB): Crucial PC4-21300 + Kingston PC4-17100
    iGPUIntel HD Graphics 530 (Skylake-S GT2)
    Storage250 GB (ssd)
    BootloaderOpenCore (latest)

    ❗ Problem Summary:

    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 🚫. 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:


    1. Boot to OpenCore picker → Works ✅

    2. 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
  1. Photos attached: Images
    • OpenCore Picker
    • Black screen with prohibited sign
    • Boot log with error messages

🔎 Diagnosis:

SymptomMeaning
OCS: No schema for LegacyEnableMinor warning — leftover/obsolete key from previous OpenCore versions. Harmless.
🚫 Prohibited SignCritical — the installer cannot find a valid environment or missing drivers.
OCB: StartImage failedOpenCore failed to load the macOS installer image properly. Fatal error.

🛠 Possible Causes + Solutions:

AreaAction
Config.plistRemove the LegacyEnable key. Validate the config using ProperTree or OpenCore Configurator.
SMBIOSUse a modern SMBIOS (recommend: iMac17,1).
SecureBootModelSet to Default or Disabled under Misc > Security.
KextsMake sure you're using the latest versions: Lilu, WhateverGreen, VirtualSMC, AppleALC, NVMeFix, etc.
UEFI DriversEnsure you're using: OpenRuntime.efi, OpenCanopy.efi, and HfsPlus.efi.
ACPILoad basic SSDTs: SSDT-PLUG, SSDT-EC-USBX, SSDT-AWAC (for Skylake timer fix).
USB MappingSequoia enforces stricter USB mapping. Build a proper USB map using USBToolBox.
Installer USBDouble-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-id is 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! 🙏
View attachment 9292
Attach the complete EFI you're using to boot.
 
still error :
Your EFI is not as per the guide.

Start here:

Regarding the error, add SSDT-SWAC-DISABLE.aml and then check.
after going through the video

Here the link for new efi that i made according to the video file
 

Attachments

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Last edited:
still error :

after going through the video

Here the link for new efi that i made according to the video file
Still not as per the guide. Important kexts are missing and ACPI Quirks are not correctly configured.

Also, as macOS Sequoia is not supported SKL CPUs, you'll have to use a different SMBIOS for macOS Sequoia. You can use iMac18,2 or 18,3.
 
Still not as per the guide. Important kexts are missing and ACPI Quirks are not correctly configured.

Also, as macOS Sequoia is not supported SKL CPUs, you'll have to use a different SMBIOS for macOS Sequoia. You can use iMac18,2 or 18,3.
After your reccomdeation i move to new machine

System Specs:​

ComponentDetails
MotherboardMSI H110M PRO-VH PLUS (MS-7A15)
ChipsetIntel H110 (Skylake PCH-H)
CPUIntel Core i3-7100 (Kaby Lake, LGA1151)
RAM8GB DDR4 2400 MT/s (M4U08S681LJJJ43-12)
iGPUIntel HD Graphics 630 (Kaby Lake-S GT2)
BootloaderOpenCore (latest, presumably 0.9.9+)
BIOS VendorAmerican Megatrends
BIOS Version1.C0 (UEFI Capable)
BIOS Date06/16/2018
Super I/ONuvoton NCT6793D/NCT5563D
 
After your reccomdeation i move to new machine

System Specs:​

ComponentDetails
MotherboardMSI H110M PRO-VH PLUS (MS-7A15)
ChipsetIntel H110 (Skylake PCH-H)
CPUIntel Core i3-7100 (Kaby Lake, LGA1151)
RAM8GB DDR4 2400 MT/s (M4U08S681LJJJ43-12)
iGPUIntel HD Graphics 630 (Kaby Lake-S GT2)
BootloaderOpenCore (latest, presumably 0.9.9+)
BIOS VendorAmerican Megatrends
BIOS Version1.C0 (UEFI Capable)
BIOS Date06/16/2018
Super I/ONuvoton NCT6793D/NCT5563D
You can now follow the guide and configure the EFI for KBL.
 
Still not as per the guide. Important kexts are missing and ACPI Quirks are not correctly configured.

Also, as macOS Sequoia is not supported SKL CPUs, you'll have to use a different SMBIOS for macOS Sequoia. You can use iMac18,2 or 18,3.
After your recommendation, I have update the configuration of system :

System Specs:​

ComponentDetails
MotherboardMSI H110M PRO-VH PLUS (MS-7A15)
ChipsetIntel H110 (Skylake PCH-H)
CPUIntel Core i3-7100 (Kaby Lake, LGA1151)
RAM8GB DDR4 2400 MT/s (M4U08S681LJJJ43-12)
iGPUIntel HD Graphics 630 (Kaby Lake-S GT2)
BootloaderOpenCore (latest, presumably 0.9.9+)
BIOS VendorAmerican Megatrends
BIOS Version1.C0 (UEFI Capable)
BIOS Date06/16/2018
Super I/ONuvoton NCT6793D/NCT5563D

in this new config with this efi and a new error : here
 
Were you able to create the EFI using the guide?
 

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