Fix Legacy Boot is Greyed Out in BIOS. The UEFI mode of BIOS is better than the Legacy mode in a number of ways. Because of this, the Legacy BIOS mode isn’t used as much since UEFI came out. UEFI has many benefits, such as a faster boot time, support for hard drives that are bigger than 2 TB, secure boot, etc.
Secure boot is not supported in Legacy BIOS mode. So, computers that use UEFI BIOS mode are safer than computers that use Legacy BIOS mode. You can switch between Legacy and UEFI modes if your BIOS supports both.
But after turning on the UEFI BIOS mode, some users can’t switch back to the Legacy BIOS mode. When they tried to do this, they saw that the Legacy Boot option in BIOS was grayed out. In this article, we’ll look at why the Legacy Boot option is grayed out in BIOS and what can be done to fix it.
Fix: Legacy Boot is Greyed Out in BIOS
Turn off Trusted Platform Technology
- Boot into the Windows Recovery Menu.
- Enter your BIOS utility.
- Open the Security tab using the right and left arrow keys.
- Highlight the TPM State option and press Enter. If no TPM option is available, look for the PTT option.
- Select Disabled to disable TPM on your device.
- Press F10 to save the change and exit.
Disable Modern Standby
- To open the Run box, press the Windows key + X.
- By clicking on Windows Terminal (Admin), you can open the terminal as an administrator.
- Copy and paste the following reg command into the Terminal window: add the following to the registry: reg add HKLMSystemCurrentControlSetControlPower /v PlatformAoAcOverride /t REG_DWORD /d 0.
- Close the Command Prompt when you see the message “Operation completed successfully.”
- To use the changes, you need to restart your PC.
Disable Secure Boot to Enable Boot
- Click the “Start” button and then choose “Power.”
- Hold the Shift key down.
- Click on “Restart,” and if asked, confirm the action.
- As the PC shuts down and starts up into the Recovery Menu, let go of the Shift key.
- Click on Advanced options in the Troubleshoot menu.
- Press the UEFI Firmware Settings button.
- To get to the Startup Menu, click “Restart.”
- Press F10 at the Start-Up Menu to get to the BIOS Settings. Depending on who made your computer, you may also see other options.
- You can open the Boot Options tab in the BIOS Utility by using the right and left arrow keys.
- Use the up and down arrow keys to select the Secure Boot option, then press Enter to see more choices.
What Causes the Legacy Boot Grayed Out Problem?
If UEFI settings like Secure Boot and TPM are turned on in the BIOS utility, the Legacy Boot option may be grayed out. The BIOS utility can sometimes tell you why you can’t change to the Legacy boot option. Open the Advanced Boot Options menu in your BIOS tool.
Then, check the box next to Enable Legacy Option ROMs. You might get an error message that tells you why the Legacy option can’t be turned on. Most of the time, it means that PPT/TPM or Secure Boot is turned on. If you don’t have this option, follow the steps below to fix the problem and get the Legacy boot option back in BIOS.
Secure Boot in BIOS is greyed out if the administrator password is not set. In other instances, incorrect BIOS security settings and outdated BIOS can cause the issue. As a last resort, try to restore BIOS settings to factory defaults to restore Secure Boot in BIOS.
The most common reason for Legacy Boot being greyed out or failing to switch from UEFI to Legacy is Secure Boot. Secure Boot is one of UEFI’s requirements. You cannot switch from Legacy BIOS mode to UEFI BIOS mode until Secure Boot is enabled on your system.
If the boot device priority is not selectable that likely means your BIOS is set to UEFI/Secure Boot. If you change the boot type to ‘Legacy’, you should be able to change/set the boot priority. Keep in mind modifying your BIOS settings can cause your system to become unbootable.