Windows, in general, and Windows 11, in particular, is a very interesting operating system. It has features that can sometimes be a little confusing, especially when it comes to disk encryption. For example, while it shows that the C drive is encrypted with BitLocker, if you go into BitLocker management, it might prompt you to activate BitLocker, suggesting that it’s not enabled. This can lead to some issues when you attempt to install another operating system, like Linux, alongside your existing Windows installation on the same drive.
When you boot the Linux setup image and try to repartition the drive for the Linux installation, you might find that you’re unable to shrink the Windows partition, as it is still encrypted with BitLocker. However, there’s a twist. Windows doesn’t only have the BitLocker encryption, which is available on Pro and Enterprise versions of Windows, but it also includes a feature called device encryption. This is a different encryption method used on lower-tier Windows versions, like Windows Home.
To resolve this, you need to go into the new Windows settings, navigate to the “Privacy & Security” section, and look for a special option called Device Encryption. You will only see this section if your device has both TPM (Trusted Platform Module) and Secure Boot enabled in the BIOS. Once you locate the device encryption slider, you can simply switch it from the “On” position to the “Off” position.
After doing this, Windows will start decrypting the files on your drive. Once the decryption process is finished, the drive will no longer appear as encrypted, and the BitLocker management tool will stop prompting you to activate BitLocker. At this point, you can go back to your Linux installation, and the drive will no longer be flagged as BitLocker-encrypted, allowing you to repartition it as needed.