Drivers · critical

How to fix ACPI_BIOS_ERROR BSOD

Drivers troubleshooting guide

What this error means

Windows stops with ACPI_BIOS_ERROR (0x000000A5) during boot because the system BIOS is not ACPI compliant or has bugs.

Updated

Before you begin

Save open work and back up important files. Use instructions for your exact device and software version. If Windows cannot start, see the startup guide.

Work through these checks

0 of 3 complete
01Update BIOS to the latest version from the manufacturer
  1. Update BIOS to the latest version from the manufacturer
What to expect

Check whether the original symptom still occurs.

If it does not help

Continue only if this check applies to your device. Consult its manufacturer if you are unsure.

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02Disable advanced C-States and S-States in BIOS
  1. Disable advanced C-States and S-States in BIOS
What to expect

Check whether the original symptom still occurs.

If it does not help

Continue only if this check applies to your device. Consult its manufacturer if you are unsure.

Browse related errors
03Boot with /NOACPI flag to diagnose: bcdedit /set {default} detecthal yes
  1. Boot with /NOACPI flag to diagnose: bcdedit /set {default} detecthal yes
What to expect

Check whether the original symptom still occurs.

If it does not help

Continue only if this check applies to your device. Consult its manufacturer if you are unsure.

Browse related errors

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

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