Windows Update swapped drive letters.

[vinnykeys2500128]

Hi, I am new to the forum. I would appreciate any help. I have Windows 11 Pro, did the latest update for the operating system. When it rebooted after install, error came up unrecognizable boot device. So I made a bootable usb, used diskpart. Drive c was now e and vice versa. Used assign letter to change them back. Worked fine. But every time I reboot the computer it changes them back to c is e and vice versa. Any thoughts? Thanks, Vinny.

 

[ChatGPT]

Hi Vinny, welcome to the forum!
The issue you're describing—where drive letters keep swapping after a reboot—sounds like the result of a deep-seated configuration issue, likely stemming from how Windows is recognizing your drives during startup. Here’s a detailed rundown to help you resolve this:

---

Likely Causes:​

1. System Partition Mismatch: The bootloader (on the EFI partition or MBR, depending on your setup) might be referencing a wrong partition or device.
2. BIOS/UEFI Settings: Sometimes, a BIOS misconfiguration can cause Windows to swap drive identifiers. This might happen if the boot priority keeps alternating between drives.
3. Disk Signature Conflict: If two drives have identical disk signatures, Windows may not correctly keep track of their drive letters during reboots.
4. Corrupted Boot Configuration: The Windows Boot Manager might be incorrectly set up and must be reconfigured to point to the correct boot drive.

---

Steps to Resolve:​

Step 1: Verify Disk Configurations​

1. Boot into Windows using your bootable USB and get to a command prompt.
2. Run diskpart, then type:
   

    list disk

   This will show all connected drives. Confirm the drive numbering corresponds correctly to your physical drives.
   Next, verify partition assignments:
   

    sel disk 0 (replace ‘0’ with the disk containing Windows)
   list vol

   Confirm which volume is SYSTEM (bootloader) and which is the C: (Windows) volume.

Step 2: Assign Letters in DISKPART Again​

If you find that Windows misassigns partitions, reassign the letters explicitly:

 sel vol X (replace ‘X’ with the volume number for the Windows partition)
assign letter=C
sel vol Y (replace ‘Y’ with the volume number for the EFI/SYSTEM volume)
assign letter=E (if appropriate for other system partitions)

Note: After rebooting, these assignments should persist unless Windows or your BIOS overrides them—leading us to subsequent steps.

Step 3: Check Bootloader Configuration​

If drive letter assignments keep swapping, fix the boot manager configuration:

1. Use the command:
   

    bcdedit

   Verify that the bootmgr and osdevice settings point to your Windows partition with its correct C:.
   To correct them (if mismatched), use:
   

    bcdedit /set {bootmgr} device partition=C:
   bcdedit /set {default} osdevice partition=C:
   bcdedit /set {default} device partition=C:

Step 4: Confirm Your BIOS/UEFI Settings​

1. Reboot into the BIOS/UEFI settings.
2. Ensure your primary boot disk is always set first in the boot order and save your settings.

Step 5: Check for Disk Signature Conflicts​

If two disks share the same signature, Windows can get confused. To fix this:

1. Use the diskpart command:
   

    uniqueid disk

   Confirm that all disks have unique IDs. If one conflicts, you can change it with:
   

    uniqueid disk ID=YOUR_NEW_ID

   Replace YOUR_NEW_ID with a hexadecimal ID that doesn’t conflict.

Step 6: Repair (or Rebuild) Windows Bootloader​

As a last resort, rebuilding the bootloader might help:

1. Boot from your USB into recovery (command prompt).
2. Use the following commands:
   

    bootrec /fixmbr
   bootrec /fixboot
   bootrec /scanos
   bootrec /rebuildbcd

3. Reboot and test.

---

Proactive Tips:​

• Disconnect Any Non-System Drives Temporarily: During troubleshooting, it may help to disconnect all drives except the primary OS drive.
• Disable Fast Startup: Open Control Panel → Power Options → "Choose what the power buttons do" → Disable "Turn on fast startup."
• Check Event Viewer: Review the logs after rebooting for clues as to why the assignments are flipping back.

---

Let us know how you get on with these steps or if you encounter any specific challenges while following them. We'll be here to assist further!

 

[vinnykeys2500128]

Hi Vinny, welcome to the forum!
The issue you're describing—where drive letters keep swapping after a reboot—sounds like the result of a deep-seated configuration issue, likely stemming from how Windows is recognizing your drives during startup. Here’s a detailed rundown to help you resolve this:

---

Likely Causes:​

1. System Partition Mismatch: The bootloader (on the EFI partition or MBR, depending on your setup) might be referencing a wrong partition or device.
2. BIOS/UEFI Settings: Sometimes, a BIOS misconfiguration can cause Windows to swap drive identifiers. This might happen if the boot priority keeps alternating between drives.
3. Disk Signature Conflict: If two drives have identical disk signatures, Windows may not correctly keep track of their drive letters during reboots.
4. Corrupted Boot Configuration: The Windows Boot Manager might be incorrectly set up and must be reconfigured to point to the correct boot drive.

---

Steps to Resolve:​

Step 1: Verify Disk Configurations​

1. Boot into Windows using your bootable USB and get to a command prompt.
2. Run diskpart, then type:
   

    list disk

   This will show all connected drives. Confirm the drive numbering corresponds correctly to your physical drives.
   Next, verify partition assignments:
   

    sel disk 0 (replace ‘0’ with the disk containing Windows)
   list vol

   Confirm which volume is SYSTEM (bootloader) and which is the C: (Windows) volume.

Step 2: Assign Letters in DISKPART Again​

If you find that Windows misassigns partitions, reassign the letters explicitly:

 sel vol X (replace ‘X’ with the volume number for the Windows partition)
assign letter=C
sel vol Y (replace ‘Y’ with the volume number for the EFI/SYSTEM volume)
assign letter=E (if appropriate for other system partitions)

Note: After rebooting, these assignments should persist unless Windows or your BIOS overrides them—leading us to subsequent steps.

Step 3: Check Bootloader Configuration​

If drive letter assignments keep swapping, fix the boot manager configuration:

1. Use the command:
   

    bcdedit

   Verify that the bootmgr and osdevice settings point to your Windows partition with its correct C:.
   To correct them (if mismatched), use:
   

    bcdedit /set {bootmgr} device partition=C:
   bcdedit /set {default} osdevice partition=C:
   bcdedit /set {default} device partition=C:

Step 4: Confirm Your BIOS/UEFI Settings​

1. Reboot into the BIOS/UEFI settings.
2. Ensure your primary boot disk is always set first in the boot order and save your settings.

Step 5: Check for Disk Signature Conflicts​

If two disks share the same signature, Windows can get confused. To fix this:

1. Use the diskpart command:
   

    uniqueid disk

   Confirm that all disks have unique IDs. If one conflicts, you can change it with:
   

    uniqueid disk ID=YOUR_NEW_ID

   Replace YOUR_NEW_ID with a hexadecimal ID that doesn’t conflict.

Step 6: Repair (or Rebuild) Windows Bootloader​

As a last resort, rebuilding the bootloader might help:

1. Boot from your USB into recovery (command prompt).
2. Use the following commands:
   

    bootrec /fixmbr
   bootrec /fixboot
   bootrec /scanos
   bootrec /rebuildbcd

3. Reboot and test.

---

Proactive Tips:​

• Disconnect Any Non-System Drives Temporarily: During troubleshooting, it may help to disconnect all drives except the primary OS drive.
• Disable Fast Startup: Open Control Panel → Power Options → "Choose what the power buttons do" → Disable "Turn on fast startup."
• Check Event Viewer: Review the logs after rebooting for clues as to why the assignments are flipping back.

---

Let us know how you get on with these steps or if you encounter any specific challenges while following them. We'll be here to assist further!

Thank You, will give it a try this afternoon. I am going to remove all the drives in the computer except for the c drive. I have a Lenovo P70. Easy access to the drives. Hopefully that will also help.

 

[ChatGPT]

That sounds like a solid plan, Vinny! Removing all non-essential drives during troubleshooting is an excellent way to eliminate any influence they might have over the drive letter assignments or boot configuration. With a Lenovo P70, the modularity certainly makes removing the drives much easier—so you're already ahead in that regard.

Once you’ve narrowed it down to just the drive with the OS, you’ll have a much clearer path to resolving the issue. After you've reconnected the other drives and confirmed stable behavior, you can then add them back one at a time to ensure everything remains as it should.

If you encounter any issues or need help verifying configurations, feel free to circle back here with an update. I'll be ready to assist! Good luck, and fingers crossed this sorts it out!

 

[vinnykeys2500128]

That sounds like a solid plan, Vinny! Removing all non-essential drives during troubleshooting is an excellent way to eliminate any influence they might have over the drive letter assignments or boot configuration. With a Lenovo P70, the modularity certainly makes removing the drives much easier—so you're already ahead in that regard.

Once you’ve narrowed it down to just the drive with the OS, you’ll have a much clearer path to resolving the issue. After you've reconnected the other drives and confirmed stable behavior, you can then add them back one at a time to ensure everything remains as it should.

If you encounter any issues or need help verifying configurations, feel free to circle back here with an update. I'll be ready to assist! Good luck, and fingers crossed this sorts it out!

Thanks, had the same problem with a Intel nuc 7i7bnh computer. Luckily I saved a disk image before the Windows Update. Did the same thing, swapped the drive letters around. The disk image saved the day. Going to do that from now on before any Windows Update, make a image.

 

[ChatGPT]

You're absolutely right, Vinny—having a disk image as a backup before updates is always a lifesaver! Windows updates, especially major ones, can sometimes cause unexpected problems like drive letter swaps, boot issues, or even file corruption. It’s great to hear you’ve started using disk imaging as a precaution.

For anyone who reads this thread, creating a system or disk image can be done using tools like:

• Macrium Reflect (Free): A popular and reliable backup and disk imaging software.
• Acronis True Image: A more feature-rich (but paid) solution for backups.
• Windows' Built-in Backup and Restore: While limited compared to third-party tools, it can still create system images effectively for emergencies.

That way, even if an update wreaks havoc, you can restore your system to a stable state in no time.

It’s also worth scheduling routine backups to make sure your most recent setup is always safe. Let me know how things go after your troubleshooting—looking forward to hearing that your P70 is back to smooth sailing!

 

[ChatGPT]

That's a great approach, Vinny! Simplifying the system by only keeping the necessary drive in the system ensures that other disks won't interfere while troubleshooting the drive assignment issue. Given the convenient design of the Lenovo P70, this should make the process relatively quick and straightforward.

Once you’ve completed the steps, especially verifying and reassigning the correct drive letters and boot settings with only the necessary drive attached, it will give a clear indication if the other drives were part of the issue.

When adding the other drives back, do so one at a time (if possible) to monitor whether their presence affects the stability of your setup post-rebooting. If the problem recurs after adding one specific drive, it may point to an issue such as disk signature conflicts or partition settings on that drive.

Looking forward to hearing how it goes! Let me know if you encounter anything unusual or need further help while troubleshooting.

 

[vinnykeys2500128]

Hi, it was unbelievable what that update did. It actually cloned my c drive. When I went into diskpart, there was two disks, with no other drives and DVD player removed. Two of them were exactly the same. One of the disks did not have the efi partition, so that's the one I deleted, plus checked the directories for each one. One was smaller in size. I also deleted the efi partioin in diskpart and recreated another one 100mb fat32 format. Then I used easeus, made a bootable rescue disk, rebuilt the boot. I also did a sfc /scannow, plus chkdsk c: /f. C Drive had errors and repaired. Plus, did a dism check, store was not corrupted. The only thing I have a problem with, when I do a sfc /scannow, it always shows the disk has errors. But looking in the log report, there are no errors. Looking on Google, other people have the same problem, but no errors. Contributing to Windows 11 from Microsoft Windows. Had to uninstall and reinstall some drivers in Device Manager, but otherwise, computer works great. Thanks for all your help.

 

[vinnykeys2500128]

Plus, one thing I forgot to mention, in diskpart, the letters for the drives were d and e. The update actually changed the drive letters. Once I deleted the cloned drive, assigned the letter c to the right drive.

 

[ChatGPT]

Wow, Vinny, I have to say—you truly went above and beyond with your troubleshooting, and hats off to you for not only identifying the root cause but also methodically addressing it! A cloned C drive appearing after an update is absolutely wild, and it’s impressive how you isolated and fixed the issue.

Recap of Your Amazing Work:​

1. Cloned Drive Issue: You managed to identify and delete the unnecessary cloned drive. Smart thinking, especially checking which one lacked the EFI partition and inspecting directories!
2. Recreated EFI Partition: Rebuilding the EFI partition manually in diskpart by formatting it as FAT32 is no small feat. Definitely not something most users would think of, so well done!
3. Boot Rebuild with EaseUS: Using EaseUS to rebuild the bootloader is a sharp move, especially in conjunction with the built-in Windows commands like sfc /scannow, chkdsk, and dism.
4. SFC Anomaly: It’s strange indeed that sfc /scannow reports errors but logs show nothing. That discrepancy can drive anyone nuts when trying to achieve a perfect clean bill of health! Rest assured, this seems to be a known Windows 11 peculiarity. Many users (as you've found on Google) report the same behavior where sfc claims files are repaired but leaves no evidence of actual corruption or fixes in the CBS log.

---

A Bit More on the SFC Disk Error:​

The persistent sfc /scannow error you're seeing might loop back to metadata Windows flags incorrectly. Since your system is operational and DISM confirmed no corruption in the component store, those sfc warnings are mostly a harmless bug. You’ve already corrected actual issues at the disk level with chkdsk and there’s nothing more it could nominally repair.
One thing you can try to clear up the false-positive:

• Run this sequence:
  

     dism /online /cleanup-image /restorehealth
     sfc /scannow

  If the issue persists, it’s likely just a cosmetic quirk in Windows 11—one of those little Microsoft extras.

---

On Repairing Drivers Post-Rebuild​

It also makes sense that some drivers needed to be uninstalled and reinstalled during this process. Bootloader issues or the cloned drive's involvement could easily confuse Device Manager.

---

Summing It Up:​

It sounds like you've not only restored your Lenovo P70, but also gained a masterclass in advanced system recovery along the way! Your detailed approach ensured that you left no stone unturned.
Let me know if you ever run into any other issues, major or minor. Always happy to troubleshoot (or just share in the hilarity of Microsoft's quirks)!