That screenshot means File History is
enabled, but Windows has decided the target volume
Q: (“FileH+-Len”) is
not a valid File History target, so it shows:
- “File History doesn’t recognize this drive”
- “Unknown error”
This is usually caused by
File History’s database/config getting confused or Windows seeing the external disk as “not suitable” (unstable connection / removable classification / previous File History set pointing somewhere else).
Below is the simplest, safest,
GUI-only fix sequence.
A) Reset File History (no formatting)
Do this on the PC where you’re seeing the message.
1)
Turn File History off
- Control Panel → System and Security → File History
- Click Turn off
2)
Unplug the Samsung T7, wait 10 seconds, plug it back in (use your C‑to‑C cable)
3)
Select the drive again
- Back in File History, click Select drive
- Pick the partition you want (by Volume Label, not letter)
- Click OK
4) Click
Turn on, then click
Run now
If it works, great.
If it still says “doesn’t recognize this drive / unknown error,” do B.
B) Remove old File History data on that partition (still no formatting)
This fixes the common “unknown error” loop.
1) On the Q: partition, open
File Explorer → This PC → open
Q:
2) If you see a folder named
FileHistory on Q:,
delete it.
- If you don’t see it: File Explorer → View → Show → turn on Hidden items, then look again.
3) Go back to Control Panel → File History:
- Select drive again
- Turn on
- Run now
If it works after deleting
Q:\FileHistory, you’re done.
C) If it STILL won’t recognize Q: (most likely cause)
At that point, File History is usually rejecting the drive because Windows is treating the
device/connection as unreliable (even if you can copy files manually).
Two very practical options:
Option C1 (recommended): dedicate one partition to File History and reformat just that partition
If Q: doesn’t have much you care about yet:
- Disk Management → right‑click Q: → Format… → NTFS (Default allocation unit) → Quick format
Then repeat step A (Select drive → Turn on → Run now).
Option C2: choose a different partition (or a different external) for File History
Sometimes File History will accept one NTFS partition on the same disk but not another (it’s picky about whatever it thinks it saw earlier).
Also: why your “Safely remove… device is in use” keeps happening
If File History is ON, Windows can keep the disk “in use” constantly. When you want to unplug the Samsung:
1)
Turn File History off first
2) Close File Explorer windows
3) Then try
Safely Remove
Quick question (so I give the correct “next step”)
Do you currently have any important data already stored on
Q: that you don’t want to lose? (Yes/No)
- If No, the fastest reliable fix is format just Q: as NTFS and reselect it in File History.
- If Yes, we’ll do only the non-destructive reset steps (A + B) and then I’ll have you check one specific setting.