How to fix hardlock.sys blue screen error when updating

The issue combines a blue screen during/after update with BitLocker prompts and instability after sign‑in. From the available information, the supported next steps focus on:

1. Unlocking or decrypting the drive so the system can boot and be serviced.
2. Using Windows recovery options (Safe Mode or System Restore) once BitLocker is out of the way.

Because the question mentions being able to enter the BitLocker key but not what to do next, the most relevant supported path is to temporarily turn off BitLocker/device encryption from Windows Recovery, then restart and repair.

1. Decrypt the system drive from Windows Recovery

Use this if the device is prompting for the BitLocker key and then failing to boot or crashing.

1. When prompted, enter the correct BitLocker recovery key and continue.
2. On the recovery screen, select Advanced options.
3. Select Troubleshoot.
4. Select Advanced options.
5. Select Command Prompt.
6. Choose the account shown and enter its password.
7. In Command Prompt, turn off BitLocker on the system drive (assuming it is C:):

      manage-bde -off c:
   

8. Check decryption progress:

      manage-bde -status c:
   

9. Wait until Conversion Status shows Fully Decrypted.
10. Type exit to close Command Prompt.
11. Choose Continue to restart the PC.

At this point the drive is decrypted, which avoids repeated BitLocker recovery during boot and lets Windows start so that the faulty driver or update can be removed or repaired.

2. Use Safe Mode or System Restore to roll back changes

Once BitLocker is out of the way, use Windows Recovery to get into Safe Mode or restore to a point before the crashes.

Option A – Safe Mode

1. From a normal boot, on the sign‑in screen hold Shift and select Power > Restart.
2. After restart, on Choose an option, select Troubleshoot.
3. Select Advanced options > Startup Settings > Restart.
4. After restart, press 4 to Enable Safe Mode.
5. Sign in. In Safe Mode, remove or update the problematic driver or software that installed hardlock.sys.

If the system cannot reach the sign‑in screen reliably, use the same Safe Mode steps from the Windows Recovery screen instead of from a running desktop.

Option B – System Restore

If Safe Mode is unstable or the problem started immediately after an update:

1. From the Choose an option screen, select Troubleshoot > Advanced options > System Restore.
2. If asked for a BitLocker key, retrieve it as described in the BitLocker recovery key documentation (for example, via https://aka.ms/aadrecoverykey if the device is Azure AD‑joined, as shown in the CrowdStrike article in the context).
3. Select a restore point dated before the update that introduced the error.
4. Confirm and let System Restore complete.

System Restore rolls back system files, drivers, and registry to the earlier point but is designed not to affect personal files.

3. Re‑enable device encryption after repair

Once the system is stable again and the faulty driver or update is removed or replaced, device encryption can be turned back on:

1. Open Settings.
2. Go to PC and devices (or the equivalent section in Windows 11, such as Privacy & security > Device encryption).
3. Turn Device encryption back On.

This restores BitLocker/device encryption protection after the root cause has been addressed.

If crashes persist even after decrypting and rolling back via Safe Mode or System Restore, further analysis of the specific third‑party driver (hardlock.sys) and its update path would be required, but those details are not covered in the provided material.

References:

• System crashes after you restart or wake up the computer in Windows 8.1 or Windows RT 8.1
• KB5042421: CrowdStrike issue impacting Windows endpoints causing an 0x50 or 0x7E error message on a blue screen
• Bug check 0x7B: INACCESSIBLE_BOOT_DEVICE
• Prompted for BitLocker recovery key after installing updates to Surface UEFI or TPM firmware on Surface device
• Restart failure if Device Guard or Credential Guard isn't disabled correctly in Windows 10 Version 1607