What does Windows error code 4428 (ERROR_SECUREBOOT_POLICY_UNKNOWN) mean?

 
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ERROR_SECUREBOOT_POLICY_NOT_AUTHORIZED ERROR_SECUREBOOT_POLICY_MISSING_ANTIROLLBACKVERSION

ERROR_SECUREBOOT_POLICY_UNKNOWN

ERROR_SECUREBOOT_POLICY_UNKNOWN (LRESULT 0x0000114C) This Win32 error means the device does not recognize the supplemental Secure Boot policy.

What to check for ERROR_SECUREBOOT_POLICY_UNKNOWN

  • Check the policy identity, publisher, version, and target platform against the active base policy.
  • Verify that the intended base policy is present before attempting to add the supplemental policy.
  • Collect Code Integrity events that identify the policy load or validation failure.

Read-only checks

Get-SecureBootPolicy | Format-List
Get-WinEvent -LogName 'Microsoft-Windows-CodeIntegrity/Operational' -MaxEvents 50

Secure Boot policy and UEFI-variable changes can affect whether a device boots. For ERROR_SECUREBOOT_POLICY_UNKNOWN, capture the current state first and use only the approved signed policy or OEM workflow for changes.

Microsoft: Get-SecureBootPolicy

Microsoft: Viewing Code Integrity events

Microsoft: Set-SecureBootUEFI

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