Software⏱️ 4 min read📅 2026-06-11

How to Fix: Grub2 fails to chainload Windows 7 with error "invalid signature"

Grub2 fails to chainload Windows 7 with error invalid signature

Quick Answer: Check the UEFI firmware settings and ensure that the bootmgfw.efi file has a valid signature.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. 🛠️ Step-by-Step Verified Fixes
  3. 🎯 Final Words

The error 'invalid signature' when trying to chainload Windows 7 from GRUB can be frustrating, especially if you have multiple operating systems installed on your UEFI 64-bit system. This issue typically affects users who have installed both Windows and Linux on separate hard drives using the same UEFI firmware.

Despite having a clear understanding of how to use GRUB, this error can still occur due to various reasons such as incorrect boot settings or missing necessary files during installation.

⚠️ Common Causes

  • The primary reason for this error is that Windows 7 uses a different Boot Configuration Data (BCD) file than Linux. When you installed Windows 7, it created a BCD store in the EFI system partition, which includes the bootmgfw.efi file. However, GRUB does not recognize this file as a valid UEFI boot loader. This is because Windows 7 uses a different signing mechanism for its boot loaders, which GRUB may not be able to verify.
  • Another possible reason for this error is that the GRUB configuration was not properly set up during installation. If the GRUB menu was not configured correctly, it may not recognize the bootmgfw.efi file or may not have the necessary permissions to chainload Windows 7.

🛠️ Step-by-Step Verified Fixes

Reconfigure GRUB to use the correct UEFI boot loader

  1. Step 1: Open a terminal and edit the GRUB configuration file using the following command: `sudo grub-edit-config --device=hd1,gpt1 /etc/default/grub` This will open the default GRUB configuration file in the editor. Add the following line to the end of the file: `set uuid=$(blkid -o uuid -s UUID_FILE -p $(uuidgen))` This sets the UUID for the EFI system partition, which is required for UEFI boot loaders.
  2. Step 2: Save and exit the editor. Then, run the following command to update the GRUB configuration: `sudo grub-mkconfig --load all` This updates the GRUB configuration file with the new settings.
  3. Step 3: Reboot your system and enter the GRUB menu. Choose the option for the command line and type `grub> chainloader (hd1,gpt1)/efi/Microsoft/Boot/bootmgfw.efi` to attempt to chainload Windows 7.

Use a boot loader that supports UEFI boot loaders

  1. Step 1: Install a different boot loader, such as rEFInd or rEFMac, which are designed to support UEFI boot loaders. These boot loaders can recognize the bootmgfw.efi file and chainload Windows 7 correctly.
  2. Step 2: Follow the installation instructions for your chosen boot loader to set it up on your system.

🎯 Final Words

In summary, the 'invalid signature' error when trying to chainload Windows 7 from GRUB is typically caused by a mismatch between the UEFI boot loader and the Boot Configuration Data file used by Windows 7. By reconfiguring GRUB or using a different boot loader that supports UEFI boot loaders, you should be able to successfully chainload Windows 7.

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