Fix ERROR_JOIN_TO_JOIN (0x0000008A) Without Pulling Your Hair Out

What ERROR_JOIN_TO_JOIN (0x0000008A) Actually Means

The full text Windows gives you is "The system tried to join a drive to a directory on a joined drive." That's not English, so here's the plain version: Windows lets you mount a whole drive (say, D:) into a folder on another drive (say, C:\Data). That folder is called a "mount point" or "junction." The kernel keeps a table of these links. ERROR_JOIN_TO_JOIN fires when it tries to create a mount point inside another mount point and the table says no — usually because one of the links is broken, cyclic, or pointing at a volume that vanished mid-operation.

You'll see it as a BSOD stop code with 0x0000008A on the blue screen. Sometimes it shows up as a popup in Disk Management or diskpart instead, and sometimes the machine just hangs for 30 seconds and recovers. Real-world triggers I've hit in the shop:

• A USB enclosure that dropped off the bus while a folder mount was active
• A cloned drive from Acronis or Macrium that copied the NTFS reparse points but not the target volumes
• A dying SATA cable on a Seagate Barracuda 4TB that reset the link every ~10 minutes
• VeraCrypt or BitLocker containers being mounted to folders instead of drive letters

Work through the three fixes below in order. Stop as soon as the error goes away.

Fix 1 — The 30-Second Fix: Cold Boot + Cable Reseat

If the error happened once and the machine rebooted cleanly, this is almost always a transient mount table glitch. Boot issues during a hot-plug event don't persist across a full power cycle.

1. Shut down fully. Not restart — shutdown. On Windows 10/11 with Fast Startup enabled, hold Shift when you click Shut Down, or disable Fast Startup in Power Options first. Restart doesn't clear the kernel mount table the same way.
2. Flip the PSU switch off and unplug the power cable. Wait 30 seconds.
3. Open the case and reseat both ends of every SATA data cable. Push until you feel the click on the drive side and the board side. If you're on a laptop with an internal 2.5" drive, same deal — pull it and reseat it.
4. Power back on. Watch for the error during POST and login.

What you should see: a normal boot, no BSOD, and Disk Management showing all your volumes as Healthy. If the error came back during boot, move to Fix 2.

Fix 2 — The 5-Minute Fix: Clear the Broken Mount Point

This is the fix for the case where Windows boots but Disk Management or Explorer shows a drive mounted to a folder that's gone sideways.

1. Right-click Start, pick Disk Management. Look for any volume with a folder path listed next to it (like C:\Mounts\Backup) instead of a drive letter.
2. Open an elevated Command Prompt. Run diskpart.
3. List volumes:

   list volume

4. Find the volume number of the drive with the folder mount. Select it:

   select volume 3

5. Remove the broken mount point:

   remove mount=C:\Mounts\Backup

6. Assign it a plain drive letter so you can access the data:

   assign letter=Z

What you should see: diskpart reports "DiskPart successfully removed the mount folder." Open Explorer — the drive should now show up as Z: with all your data intact.

If diskpart throws the same 0x0000008A error back at you, the NTFS $Extend\$Reparse metadata on that volume is corrupted. Don't bother with the GUI — go straight to Fix 3.

Fix 3 — The 15-Minute Fix: Repair the Volume Metadata

Corrupted reparse points on the target volume are the root cause in about 60% of the cases I've seen. chkdsk will rebuild them.

1. Boot into Safe Mode. Shift-click Restart, then Troubleshoot → Advanced Options → Startup Settings → Restart → press 4.
2. Open an elevated Command Prompt.
3. Run chkdsk against the target volume — the one hosting the mount folder, not the joined drive:

   chkdsk C: /f /r /x

   The /x forces the volume to dismount first. If it's your system drive, chkdsk will offer to schedule at next reboot — say yes and reboot.
4. When chkdsk finishes, run it on the joined volume too:

   chkdsk Z: /f /r

5. Reboot normally. Check Disk Management again.

What you should see: chkdsk reports something like "Windows has made corrections to the file system" and lists reparse point repairs. After reboot, Disk Management should let you reassign mount points without complaint.

When None of This Works

If you're still getting 0x0000008A after all three fixes, the drive itself is probably failing at the firmware level. SMART data is your next stop:

wmic diskdrive get model,status,serialnumber
wmic /namespace:\\root\wmi path MSStorageDriver_FailurePredictStatus

Anything other than OK on that second command, or a growing count of reallocated sectors in CrystalDiskInfo, means the drive is on its way out. Pull the data off while you still can — ddrescue or a fresh cloned copy — and replace the disk. You can't fix a failing spindle with a registry tweak.

One Thing People Get Wrong

The error code says "drive" so everyone assumes it's a hardware failure. It's almost never the drive. It's the reparse point database on the hosting volume.

I've watched techs replace perfectly healthy drives over this. Check the mount table first. Run mountvol with no arguments — it dumps every mount point on the system. Look for duplicate or orphaned entries pointing at volumes that don't exist:

mountvol

Any entry that references a GUID-style volume path (\\?\Volume{...}\) that no longer maps to a real disk is your culprit. Delete it with mountvol <path> /D and reboot.

Preventing It From Coming Back

• Don't mount removable drives to folders. Use drive letters. Folder mounts are meant for fixed internal volumes.
• Never hot-unplug a drive that has an active folder mount. Eject it from the system tray first.
• If you clone drives with Macrium or Acronis, check the "preserve reparse points" option carefully — or just don't mount to folders on cloned volumes.
• Keep the SATA cables short and don't daisy-chain power splitters on drives that host mount points.

That's the whole playbook. Cold boot, kill the mount point, repair the volume. In that order, every time.