FVE_E_CONV_READ 0X8031001B: Read Failed During BitLocker Conversion

1. Bad Sectors on the Drive (The Most Common Cause)

This error pops up most often when BitLocker hits a bad sector during the initial encryption pass. The BitLocker driver tries to read every single sector on the volume to build its encryption map. If it can't read a sector, it throws FVE_E_CONV_READ (0X8031001B) right in your face. I've seen this on spinning disks with a few bad spots and on older SSDs that have started to wear out.

How to confirm and fix it

First, you need to scan the drive for bad sectors. Don't skip this step. Run chkdsk with the right flags. Here's what to do:

1. Open Command Prompt as Administrator. Hit the Windows key, type cmd, right-click it, pick Run as administrator.
2. Type chkdsk C: /f /r (replace C: with your drive letter). Press Enter.
3. If it's your system drive, Windows will say it can't lock the drive and ask if you want to schedule it for next reboot. Type Y and press Enter.
4. Restart your computer. The check will run before Windows loads. It'll take a while — could be hours on a large drive. Be patient.

After chkdsk finishes, it'll mark bad sectors as unusable and try to recover readable data from them. Then restart again, and try BitLocker encryption again. In about 80% of cases, this clears the error.

If chkdsk reports a lot of bad sectors (more than a handful), your drive is probably dying. Back up your data right now, don't wait for the fix to finish. You can do this from the same Command Prompt by copying files to an external drive.

2. A Failing Hard Drive or SSD

If chkdsk didn't find many bad sectors but the error persists, the drive itself might be on its way out. I've seen this on drives that pass a quick check but fail under the heavier read load that BitLocker applies during conversion. The error doesn't lie — the drive really can't read that sector, even if chkdsk says it's fine.

Check the drive's S.M.A.R.T. status

S.M.A.R.T. data tells you the drive's own health assessment. Here's how to get it without third-party tools:

1. Open PowerShell as Administrator (right-click Start, pick Windows PowerShell (Admin)).
2. Run Get-PhysicalDisk. Look at the HealthStatus column. If it says Warning or Unhealthy, the drive is failing.
3. For more detail, run wmic diskdrive get status. If it returns anything other than OK, it's bad.

If the drive is failing, the real fix is replacing it. Here's the short plan:

• Back up everything you can. Use a bootable Linux USB if Windows won't boot — but don't ask me to cover that here, just know it's an option.
• Replace the drive. For SSDs, Samsung and Crucial have been reliable for me. For HDDs, WD Black or Seagate BarraCuda Pro are solid.
• Reinstall Windows or clone the old drive to the new one. BitLocker will work fine on a healthy drive.

Don't try to force BitLocker on a failing drive. It'll just hang or fail again, and you risk losing data when the drive finally dies.

3. File System Corruption That chkdsk Didn't Catch

Sometimes the file system itself is slightly corrupted in a way that chkdsk with /f /r doesn't fully repair. This is less common but I've seen it on volumes that were encrypted before with a different tool (like TrueCrypt or VeraCrypt) and then reformatted. The BitLocker driver hits a weird NTFS metadata structure and can't read it.

Use SFC and DISM to check system files

While this sounds like it's about system files, it can fix underlying corruption that affects volume reads. Do this:

1. Open Command Prompt as Administrator.
2. Run sfc /scannow. Let it finish. It'll tell you if it found corrupted files and replaced them.
3. Then run DISM /Online /Cleanup-Image /RestoreHealth. This can take 15-30 minutes.
4. Reboot after both complete.

If that doesn't help, you can try a more aggressive file system check with chkdsk C: /f /r /x. The /x flag forces the volume to dismount first, which can give a deeper scan. I've seen this catch issues that the normal scan missed.

Last resort: reformat the volume

If none of the above works, and you've already backed up your data, reformat the drive. Right-click the drive in File Explorer, pick Format, choose NTFS, and do a full format (uncheck Quick Format). A full format takes longer but writes zeroes to every sector, wiping out any latent corruption. After that, BitLocker will work fine.

One more thing: if you're trying to encrypt a drive that previously had BitLocker enabled and then was decrypted, there's a known issue where the conversion metadata gets confused. In that case, use manage-bde -off C: (if it's on) then manage-bde -on C: after a reboot. That's a separate scenario, but it's worth a try if you've been turning BitLocker on and off.

Quick-Reference Summary Table

If you try all these and still get error 0X8031001B, the drive is almost certainly failing. Don't fight it. Replace the drive. Your data is worth more than the time you'll burn chasing a dead disk.