How to Fix “Error: BIOS Legacy Boot of UEFI Only Media”

Encountering the “Error: BIOS Legacy Boot of UEFI Only Media” message can be frustrating, especially when you’re trying to boot from a USB drive or other media. This error typically arises when your system’s BIOS is configured for legacy boot mode, but the bootable media is formatted for UEFI (Unified Extensible Firmware Interface) boot. This comprehensive guide will walk you through the steps to resolve this issue and successfully boot from your UEFI-only media.

Understanding the Problem

Before diving into the solutions, it’s crucial to understand why this error occurs. Modern systems use UEFI, which offers advantages like faster boot times and support for larger hard drives. However, many older systems or systems with compatibility support modules (CSM) enabled attempt to boot using the older BIOS legacy mode. When you try to boot UEFI-formatted media in legacy mode, the system can’t interpret the boot information, resulting in the error.

Solutions to Fix the Error

Here are several methods to fix the “BIOS Legacy Boot of UEFI Only Media” error:

1. Disable Legacy Boot/CSM and Enable UEFI Boot

The most direct solution is to disable legacy boot support (also known as CSM - Compatibility Support Module) in your BIOS settings and enable UEFI boot. Here’s how:

  1. Enter BIOS Setup: Restart your computer. As it boots, press the key that accesses the BIOS setup utility. Common keys include Delete, F2, F12, Esc, or others, depending on your motherboard manufacturer. Refer to your motherboard manual or the boot-up screen for the correct key.
  2. Navigate to Boot Options: Use the arrow keys to navigate through the BIOS menu. Look for options like “Boot,” “Boot Options,” “Boot Configuration,” or similar.
  3. Disable CSM/Legacy Boot: Find the “CSM Support,” “Legacy Boot,” or “Legacy BIOS Support” option. Disable it. The wording might vary, but the core concept remains the same.
  4. Enable UEFI Boot: Look for an option like “UEFI Boot,” “UEFI Boot Mode,” or similar. Enable it. Ensure that UEFI boot is prioritized over legacy boot options.
  5. Save Changes and Exit: Press the key indicated on the screen (usually F10) to save your changes and exit the BIOS setup. Your computer will restart.

2. Select the Correct Boot Device (UEFI)

Even with UEFI boot enabled, your system might not automatically boot from the UEFI media. You might need to manually select the correct boot device during startup.

  1. Access Boot Menu: Restart your computer. As it boots, press the key that accesses the boot menu. Common keys include F12, F11, Esc, or others, depending on your motherboard manufacturer. Refer to your motherboard manual or the boot-up screen for the correct key.
  2. Select UEFI Device: In the boot menu, look for an entry that identifies your bootable media with the prefix “UEFI:”. For example, it might look like “UEFI: USB Drive Name” or “UEFI: Partition 1.” Select this UEFI entry to boot from the media.

3. Reformat the Bootable Media (If Possible)

If you have the option, reformatting the bootable media can resolve the issue. You can format the media to be compatible with both UEFI and legacy BIOS, providing broader compatibility. However, this isn’t always possible, especially with media provided by a third party.

  • Using Rufus (Windows): Rufus is a popular tool for creating bootable USB drives. When creating the media, select the “GPT” partition scheme for UEFI and the “FAT32” file system for maximum compatibility. This often resolves boot issues across different systems.

  • Using dd command (Linux/macOS): Be very careful with the dd command as it can overwrite data. The safest approach is to re-download the ISO and recreate the bootable USB with Rufus in Windows or use other GUI tools in Linux.

4. Update Your BIOS

An outdated BIOS can sometimes cause compatibility issues with UEFI boot. Updating to the latest version can resolve these issues. However, proceed with caution, as a failed BIOS update can render your motherboard unusable.

  1. Identify Motherboard Model: Determine the exact model of your motherboard. This information is usually printed on the motherboard itself or can be found in your system information.
  2. Download BIOS Update: Visit the motherboard manufacturer’s website and download the latest BIOS update for your specific model. Make sure the update is compatible with your operating system.
  3. Follow Update Instructions: Carefully follow the manufacturer’s instructions for updating the BIOS. Typically, this involves placing the BIOS update file on a USB drive and using the BIOS setup utility to flash the new BIOS.

5. Secure Boot Settings

Secure Boot is a UEFI feature that prevents unauthorized operating systems from booting. While it enhances security, it can sometimes interfere with booting from certain media. Try disabling Secure Boot in your BIOS settings:

  1. Enter BIOS Setup: Restart your computer and enter the BIOS setup utility.
  2. Navigate to Security: Look for a “Security” tab or similar option.
  3. Disable Secure Boot: Find the “Secure Boot” option and disable it. Note that disabling secure boot may have security implications. Weigh the risks and benefits before proceeding.
  4. Save Changes and Exit: Save your changes and exit the BIOS setup.

Conclusion

The “Error: BIOS Legacy Boot of UEFI Only Media” can be resolved by adjusting your BIOS settings to properly recognize and boot from UEFI-formatted media. Disabling legacy boot/CSM and enabling UEFI boot is the most common solution. If that doesn’t work, try manually selecting the UEFI boot device, reformatting the bootable media, updating your BIOS, or disabling Secure Boot. By following these steps, you should be able to successfully boot from your UEFI-only media and resolve the error.