Windows Not Booting (Bootloop) Completing BitLocker PIN in CMS Mode
When attempting to boot a Windows system in certain scenarios, you may encounter a bootloop issue that requires the completion of the BitLocker PIN entry in CMS (Compatibility Support Module) mode. This issue can occur when using bootable applications such as SpinRite, which require CMS mode to be enabled in the BIOS.
Understanding BitLocker and CMS Mode
BitLocker is a full disk encryption feature included with Windows operating systems. It is designed to protect data by providing encryption for entire volumes. CMS mode is a compatibility mode that allows legacy operating systems and applications to boot on newer systems that use the Unified Extensible Firmware Interface (UEFI) and Secure Boot.
When BitLocker is enabled on a system with UEFI and Secure Boot, it is necessary to enter the BitLocker PIN during the boot process. However, if the system is booting from a legacy device or application that does not support UEFI and Secure Boot, it may be necessary to enable CMS mode in the BIOS to complete the BitLocker PIN entry and boot the system.
Enabling CMS Mode in the BIOS
To enable CMS mode in the BIOS, follow these steps:
- Restart the system and press the key to enter the BIOS setup (usually F2, F10, or DEL).
- Navigate to the Boot menu.
- Enable CMS mode (also known as Legacy Boot or Compatibility Support Module).
- Save and exit the BIOS setup.
Once CMS mode is enabled, the system should be able to boot from the legacy device or application and complete the BitLocker PIN entry.
Completing the BitLocker PIN Entry in CMS Mode
To complete the BitLocker PIN entry in CMS mode, follow these steps:
- Boot the system from the legacy device or application.
- Enter the BitLocker PIN when prompted.
- Press the key to switch to CMS mode (usually F12).
- Complete the boot process.
References
- Microsoft. (2021). BitLocker Drive Encryption. https://docs.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-drive-encryption-overview
- Microsoft. (2021). Unified Extensible Firmware Interface (UEFI). https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-biostests-uefi
- Microsoft. (2021). Secure Boot. https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-secure-boot
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