Suspend BitLocker on the volume(s) before you change partitions. If the tool still fails, fully decrypt the target volume, resize, then turn BitLocker back on.
Safe, working procedure
1) Back up the BitLocker recovery key(s):
Control Panel > BitLocker Drive Encryption > “Back up your recovery key”
Or: run in admin CMD: manage-bde -protectors -get C:
2) Suspend protection on every BitLocker volume you will touch:
GUI: Control Panel > BitLocker > “Suspend protection” (confirm)
Or: manage-bde -protectors -disable C: (repeat for D:, etc.)
Verify: manage-bde -status should show “Protection Status: Protection Off”.
3) Do the resize in one operation (tools that reboot to “PreOS mode” are fine once protection is suspended).
4) After it completes, check the file system: chkdsk C: /scan
5) Re‑enable protection: manage-bde -protectors -enable C:
If you still get an error
Some third‑party tools balk even when protection is suspended. In that case:
a) Decrypt the target volume: manage-bde -off C: (wait until 100%)
b) Resize with your tool or Disk Management/diskpart
c) Turn BitLocker back on: manage-bde -on C:
Extending C: often fails because the Recovery partition sits after C:. Fix:
1) reagentc /disable
2) Delete/move the Recovery partition, extend C:
3) reagentc /enable (Windows recreates a proper Recovery partition)
Notes and next info I need
Always suspend/decrypt before resizing, otherwise you may hit an error or get a recovery-key prompt at next boot.
Tell me: Windows version, which partition (C: or data), shrinking or extending, and the exact EaseUS error text. I can give precise commands based on your layout.