bitlocker suddenly activated on my fixed data drive

Please share your system model so that we might better assist you.

Encryption in Windows 11 is pretty confusing, I'll admit... and I don't have all the answers,  unfortunately. However, my understanding is that the way systems are shipped these days, Windows 11 (Home as well as Pro!) turns on Device Encryption during setup as long as (1) the hardware supports it and (2) you use a Microsoft account. (I don't know if this is the case when you install Windows yourself from standard installation media.) Device Encryption seems to be a version of BitLocker with fewer user controls but the same basic function. 

Note that the article above states, "Device Encryption encrypts your system and secondary drives completely. You don’t get to exclude a drive or partition." I suspect that during initial setup, your system silently encrypted everything including your E drive. When you resized C and D (reinstalling Windows?) you deleted the encryption configuration, which is why you now need the BitLocker key to read the data.

I also suspect, however, that the reason Windows requires a Microsoft account for automatic encryption is to ensure that the key gets backed up. Try this: go to Microsoft's site and log into your account. View "My Microsoft account," find your laptop under "Devices" and click "View details." Your recovery keys should, I hope,  be in a section titled "BitLocker data protection."

Hi NJDave,

Thank you for the guidance. My system model is Inspiron 5480. I connected the secondary hard disc as the E drive by myself after a while since I bought the computer, which is now encrypted with bitlocker without any advance notice.

The initial OS was Windows 10 home edition, then updated to Windows 11 home edition. I used a third party software to make a partition, AOMEI Partition Assistant, on the primary hard disc containing the C and D drive, then the secondary hard disc which was entirely E drive suddenly locked, although I did not manipulate the E drive with the partition software.

After the encryption happened, I upgraded it to Windows 11 Pro edition, hoping to unlock the drive from the control panel, which turned out to be in vain. I also tried the command prompt and powershell but they just said that the E drive was locked and so no commands were accepted.

What you stated seems to make a point.. maybe the bitlocker was silently activated on the secondary disc when being installed.

I have checked every possible Microsoft account but could not find any recovery key.. this is my personal laptop but I use the office 365 with my work account, so I asked the network provider in my company, but they were not able to find a recovery key.

I assume the computer failed to back up the recovery key. Otherwise the key was gone somewhere without noticing me.

Since upgrading to Pro version did not solve this issue, and also the command prompt and powershell did not help, I have no other ways to solve this. If the bitlocker activation is something common although the bitlocker is triggered just by arranging the partition size, I believe this is a fatal error for Microsoft that has not announced this critical issue to the users.

I would appreciate it if you could give further assistance.

Thank you very much and best regards,

Marumaru

I'm doing the best I can to figure out what happened, but I'm really just guessing based on the information at hand.

We can assume that the drives in the laptop were unencrypted while it was running Windows 10, and I suspect (but I don't know for certain) that at some point after you upgraded to Windows 11, it automatically encrypted the drives. According to the article I linked to earlier, it would have encrypted all the letter partitions, C, D, and E ("Device Encryption encrypts your system and secondary drives completely.").

I don't know what AOMEI Partition Assistant does if it encounters mounted, encrypted partitions. It would seem that something in the configuration changed when AOMEI resized C and D, though again this is just a guess. If this is the case, I don't think Microsoft would feel responsible for the result.

I took another look at this page at Microsoft Support and it's very relevant: Device encryption in Windows. It links to this page: Finding your BitLocker recovery key in Windows. That page kind of confirms my suspicion that "BitLocker likely ensured that a recovery key was safely backed up prior to activating protection." The key would be backed up in the Microsoft account that was associated with the PC at the time you installed Windows 11. If you haven't changed it, this would be the account that appears at the top left of Settings. The keys would be available at https://account.microsoft.com/devices/recoverykey. Unfortunately I can't think of anywhere else your key would be.

I think it's possible that your C and D partitions are (still) encrypted, and you should probably check. The switch to turn Device Encryption on and off is at Settings>Privacy & Security>Device Encryption, while the controls for full BitLocker are in Control Panel>System and Security>BitLocker Drive Encryption. If the drives are encrypted you should print or otherwise back up the key(s), or or possibly turn encryption off.

I recently responded to another user on the forum in a similar situation. I responded that I thought automatic encryption is a good thing; my problem is that the user is unaware that it's happening. I'm sorry if you can't recover your data from your E drive; I'm sorry to say it but that's why it's so important to have current backups.

Method 1: Try the correct BitLocker password
If the BitLocker password is not working, BitLocker encrypted drive won't be unlocked. In this situation, you must find the correct password and try again.

If you are sure the BitLocker password is correct, it means BitLocker encrypted drive has been corrupted so that BitLocker stops accepting the correct password. In this situation, try method 5 to recover data from BitLocker encrypted drive.

Method 2: Try the correct BitLocker recovery key
The BitLocker recovery key is another way to unlock the BitLocker encrypted drive when you forgot the BitLocker password or it is not working.

Regards,
John