Drivers · critical

How to fixACPI-BIOS-ERROR

ACPI_BIOS_ERROR BSOD

What this error means

ACPI_BIOS_ERROR BSOD ranks as a critical-severity system driver issue in our database. Windows stops with ACPI_BIOS_ERROR (0x000000A5) during boot because the system BIOS is not ACPI compliant or has bugs. Use the steps below to track down and fix the cause.

Before you begin

Save open work and back up important files. Note any recent driver or hardware changes. If Windows cannot start, use the startup guide first.

Work through these checks

0 of 3 complete
01Update BIOS to the latest version from the manufacturer

Update BIOS to the latest version from the manufacturer.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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02Disable advanced C-States and S-States in BIOS

Disable advanced C-States and S-States in BIOS.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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03Boot with /NOACPI flag to diagnose: bcdedit /set {default} detecthal yes

Boot with /NOACPI flag to diagnose: bcdedit /set {default} detecthal yes.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

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Possible causes

  • BIOS has a bug in ACPI table implementation
  • ACPI features like C-States or S-States misconfigured in BIOS
  • Windows update broke compatibility with BIOS ACPI tables

Useful Windows tools

These commands open Windows tools. Review any action inside the tool before applying changes.

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