The clone reported success, you swapped the drive — and Windows will not boot. Stay calm: this is the most common clone problem, and it is almost never lost data. Work through these checks in order.
✍️ Technical Anshu🪟 Windows 10 / 11⏱️ 15–30 minute fix
🎥 Watch the full video — HDD change and complete disk clone, step by step
A cloned drive that will not boot usually has a simple cause: the wrong disk is being booted, the boot mode does not match, or the small boot partitions were never copied. Your data is almost certainly fine. Start at Step 1 and do not skip ahead.
Startup error — the screen most people see
Windows Boot Manager
Windows failed to start. A recent hardware or software change
might be the cause.
Status: 0xc000000e
Info: The boot selection failed because a required
device is inaccessible.
Error wording as Windows shows it. On UEFI systems you may instead see a blue screen with INACCESSIBLE BOOT DEVICE — the fixes below cover both.
1
Boot With Only the New Drive Connected
Do this before changing any setting. Shut down, disconnect the old drive completely, and boot with only the cloned drive attached. When both identical disks are connected, the firmware and Windows can pick entries from the old disk, collide on the identical disk signature, or boot the old system silently. Half of all clone boot failures disappear at this step.
2
Check the Boot Order and the Boot Mode
Enter BIOS or UEFI setup and put Windows Boot Manager (UEFI) or the new drive itself (Legacy) first in the boot order.
Confirm the boot mode matches the disk style: a GPT disk needs UEFI mode; an MBR disk needs Legacy or CSM enabled. A mismatch gives exactly the kind of error shown above.
If you cloned from a Legacy MBR system to use on a UEFI-only laptop, the modes will never match — that disk must be converted to GPT, which is covered in its own guide in this series.
3
Did the Clone Include the Boot Partitions
Windows cannot boot from the C partition alone. If the clone copied only C — a very common mistake with partition-clone mode — there is no EFI System Partition and nothing for the firmware to start. Open your cloning tool and check: a correct full disk clone includes a small FAT32 EFI partition (about 100–300 MB) or, on MBR disks, a System Reserved partition, plus the recovery partition. If they are missing, redo the clone using whole disk clone mode.
4
Repair the Boot Files with bcdboot
If the partitions are all there but the boot configuration is damaged, one command from a Windows setup USB rebuilds it. Boot the setup USB, press Shift + F10 for Command Prompt, find the Windows partition letter with diskpart and list volume (in this environment it is often D or E, not C), then run:
bcdboot D:\Windows /s Z: /f UEFI — replace D with your Windows letter and Z with the EFI partition letter (assign one in diskpart with assign letter=Z if it has none).
For a Legacy MBR disk use bcdboot D:\Windows /s C: /f BIOS instead, pointing at the active System Reserved or C partition.
Restart and test. This is the short version for clone problems — deeper boot-store surgery belongs to the offline repair guides.
5
Run Startup Repair and Check the SATA Mode
From the same setup USB choose Repair your computer → Troubleshoot → Startup Repair and let it run once — it fixes simple boot configuration damage automatically.
If the motherboard was reset or the drive moved to another PC, check the SATA controller mode in BIOS. Windows installed under AHCI will blue-screen with INACCESSIBLE BOOT DEVICE if the mode was switched to RAID or IDE, and the reverse is also true. Set it back to what it was.
Still stuck? Disconnect everything except the new drive and a keyboard, and try again — a faulty second disk or USB device can hang the boot before Windows even starts.
🔴 Honest note: do not format or "clean" anything while troubleshooting. Your old drive is an untouched, working copy of the system. As long as it stays aside, every fix here is reversible — you can always re-clone and start over.
🎥 Watch the Complete Video Guide
The full process on a real PC — changing the HDD and cloning the complete disk, step by step.
Why does the PC boot fine when the old drive is also connected?
Because it is probably still booting from the old drive. The firmware finds the familiar boot entry first. That is exactly why the first test must be done with the old drive disconnected — it proves whether the clone itself can boot.
The clone boots but Windows is very slow on the new SSD. Why?
Check partition alignment — older tools sometimes misalign partitions on SSDs, which hurts speed. Also confirm the drive is connected to a SATA 3 port or the fastest M.2 slot, and that the old failing drive is no longer in the boot path.
Can I fix the boot without a Windows setup USB?
Sometimes — if another PC is available you can create the setup USB there in minutes with Microsoft Media Creation Tool. Without any bootable media your options are very limited, because every fix here runs from outside the broken Windows.
This guide is based on the Technical Anshu video on cloning a full disk to a new drive • Stuck on a step — ask in the video comments and the community will help 🙏