Diagnose a black screen with a blinking cursor before Windows starts

The firmware completes its initial checks, but Windows does not reach the Windows logo. The display remains black with a blinking text cursor or underscore, usually near a corner. On a Windows computer, that symptom commonly places the failure in the boot-loader phase: firmware selected something to boot, but the selected path did not reach a usable Windows loader, BCD store, boot sector, or SYSTEM registry hive.

A blinking text cursor is not the same as a movable mouse pointer. If the Windows logo, spinning dots, sign-in screen, or desktop appeared before the black screen, Windows has progressed beyond the phase covered here.

Search the complete code or phrase together with the computer model and any file path displayed. Do not use a code from an unrelated search result merely because the screen is also black.

Use this procedure when the machine passes its manufacturer or firmware screen, then shows a blinking text cursor before any Windows logo or spinning dots. It also applies when that cursor is replaced by one of the listed Windows Recovery or Windows Boot Manager messages and the Windows disk remains consistently detectable.

Do not use this procedure for a black screen with a movable mouse pointer after the Windows logo or sign-in, a Windows logo with frozen spinning dots, a blue-screen stop code, a disk that intermittently disappears, an installation or recovery USB that itself will not boot, or a known deleted EFI System Partition. Route those symptoms to the matching writeup. Do not treat a visible blinking cursor as proof that BCD is corrupt.

The exact Windows build, the original cause, and whether the last shutdown was interrupted may remain unknown. The physical target disk, the offline Windows volume, whether the disk is GPT or MBR, the existing system partition, and whether the displayed cursor appears before the Windows logo may not remain unknown.

Before you start:

Windows Recovery Environment or a working Windows 10/11 installation USB
A consistently detected Windows disk
A verified backup of important data before file-system or registry repair
Access to the one-time firmware boot menu
A copy of every readable BCD store before BCDBoot or Bootrec changes it
The original firmware boot-order settings recorded before changing them

Disconnect external hard disks, memory cards, optical discs, and unrelated USB storage. Leave the keyboard, display, and recovery media connected. Record the current firmware boot order and do not change UEFI/legacy mode, Secure Boot keys, controller mode, or partition layout while diagnosing the cursor.

In WinRE, use W: only after it has been assigned to the detected Windows volume and S: only after it has been assigned to the detected system partition. First use list volume to prove that each proposed letter is unused. If either letter already belongs to another volume, choose an unused letter and substitute it consistently throughout the commands. Stop if DiskPart does not report a successful assignment.

Do not treat a post-login mouse pointer as the same symptom as a pre-logo blinking text cursor.
Do not run BIOS/MBR Bootrec commands against a UEFI/GPT installation.
Do not mark a random partition active on a GPT disk.
Do not create, format, delete, convert, or resize a partition under this procedure.
Do not disable Secure Boot or switch UEFI/legacy mode merely to make the symptom change.
Do not replace a SYSTEM hive with an empty or stale RegBack file.
Do not repeatedly rebuild BCD after the message names a registry hive, storage device, or other different failure.

Stop if the disk is absent or intermittent, the partition table is damaged, multiple internal ESPs cannot be attributed, no Windows installation can be verified, the existing system partition is absent, the SYSTEM hive has no verified recovery source, or the proposed repair requires creating, formatting, converting, or deleting a partition.

Check the cause

Record exactly what appears before the cursor. Note whether a manufacturer logo, Windows logo, spinning dots, recovery code, or file path appeared.
Confirm that the cursor is a blinking text underscore or vertical bar, not a movable mouse pointer.
Open the one-time firmware boot menu and select the verified Windows Boot Manager entry for the target disk once.
Interpret the result:
- If Windows starts, the Windows boot files are usable and the persistent firmware boot order is wrong. Use Branch A.
- If Windows Recovery displays a code, record it and continue; Windows Boot Manager is now being reached.
- If the cursor is unchanged, inspect the disk and system partition from WinRE.
- If the disk is absent from firmware setup, stop. Windows commands cannot repair a drive the firmware cannot consistently see.
From WinRE Command Prompt, inspect disks and volumes without changing their layout:
```
diskpart
list disk
list volume
```
Identify the Windows volume by size and contents. Assign W only if it does not already have a usable letter:
```
select volume <Windows-volume-number>
detail volume
assign letter=W
detail volume
exit
```
Confirm that the second detail volume still identifies the verified Windows volume and now shows the intended letter. If it does not, stop.

Verify the installation instead of assuming its letter:

dir W:\Windows\System32\Config\SYSTEM
dir W:\Windows\System32\winload.*

Map that volume back to its physical disk and inspect its partitions:

diskpart
select volume <Windows-volume-number>
detail volume
select disk <Windows-disk-number>
detail disk
list partition

Detect the boot architecture from the layout:
- A GPT asterisk plus an existing small FAT32 partition whose partition details identify it as an EFI System Partition means UEFI/GPT.
- An MBR disk with an existing NTFS system partition marked active means BIOS/MBR.
- A small FAT32 partition alone is not sufficient; select it and use detail partition to confirm its type.
On BIOS/MBR, the active system partition can be the Windows volume itself. If the verified active partition is the same volume already assigned W:, do not assign S:; substitute W: for every BIOS-path S: in this article. Otherwise, confirm from list volume that S: is unused, assign it to the verified separate system partition, and leave DiskPart:
```
select partition <system-partition-number>
detail partition
assign letter=S
detail partition
exit
```
Stop if the assignment fails or the second detail display no longer identifies the verified system partition.

Create a backup folder and inspect the existing boot files.

UEFI/GPT:

md W:\BootRepairBackup
dir /a S:\EFI\Microsoft\Boot
copy S:\EFI\Microsoft\Boot\BCD W:\BootRepairBackup\BCD-before-blinking-cursor
bcdedit /store S:\EFI\Microsoft\Boot\BCD /enum all /v > W:\BootRepairBackup\bcd-before-blinking-cursor.txt
dir S:\EFI\Microsoft\Boot\bootmgfw.efi

BIOS/MBR:

md W:\BootRepairBackup
dir /a S:\Boot
copy S:\Boot\BCD W:\BootRepairBackup\BCD-before-blinking-cursor
bcdedit /store S:\Boot\BCD /enum all /v > W:\BootRepairBackup\bcd-before-blinking-cursor.txt
dir S:\bootmgr

If the BCD file is missing, the copy and bcdedit commands will fail. Record that result; do not fabricate a backup.

Run a read-only file-system check:
```
chkdsk W:
```
If the displayed code is 0xc000014c or 0xc0000218, or the message explicitly names \Windows\System32\Config\SYSTEM, use Branch E. Do not keep rebuilding BCD when the loader has already identified a registry-hive failure.

Branch A — The one-time Windows Boot Manager selection starts Windows

Restart into firmware setup.
Identify the same Windows Boot Manager entry that successfully started the verified disk.
Place that entry before USB, optical, network/PXE, UEFI shell, diagnostics, and unrelated disk entries. Do not alter UEFI/legacy mode or storage-controller mode.
Save, cold-start twice, and confirm that the firmware selects Windows Boot Manager without intervention.

Branch B — Try Windows Startup Repair once

In WinRE, select Troubleshoot > Advanced options > Startup Repair.
Select the verified Windows installation.
Let the repair complete once, then restart.
If the cursor or identical code returns, continue with the layout-specific branch. Repeating Startup Repair without a changed result adds no evidence.

Branch C — Valid UEFI boot files exist, but the firmware entry is missing

Reconfirm that W: is the Windows volume and S: is the existing EFI System Partition on the intended disk.
Preserve and enumerate the readable BCD as shown in the diagnosis notes. If BCD is missing or invalid, route to FIX-004 or FIX-004. If winload.efi is missing or incorrectly referenced, route to FIX-013. Do not continue this NVRAM-only branch.
Confirm that the existing loader's device and osdevice resolve to the verified Windows volume, path is \Windows\System32\winload.efi, systemroot is \Windows, and this file exists:
```
dir S:\EFI\Microsoft\Boot\bootmgfw.efi
```
Verify that WinRE itself was booted in UEFI mode:
```
wpeutil UpdateBootInfo
reg query HKLM\System\CurrentControlSet\Control /v PEFirmwareType
```
Continue only when PEFirmwareType is 0x2. If it is 0x1, shut down and boot the recovery media through its UEFI-labelled entry.
When the installation and ESP are unambiguous and the only demonstrated defect is the absent firmware entry, create or refresh that entry while preserving the existing relative boot order:
```
bcdboot W:\Windows /f UEFI /p /v
```
Open the one-time boot menu, select the new or refreshed Windows Boot Manager entry, and test twice. FIX-003 contains the dedicated missing-UEFI-entry procedure if the entry is still absent.

Branch D — BIOS/MBR boot code, BOOTMGR, or BCD is implicated

Use this branch only after DiskPart proves the Windows disk is MBR and the intended NTFS system partition is already marked active.

Preserve the readable BCD as shown in the diagnosis notes.
Do not run bootrec /fixmbr or bootrec /fixboot from this symptom router. Those commands have an implicit target; a preceding DiskPart selection does not constrain them.
Route BOOTMGR is missing, damaged BIOS boot code, missing BIOS boot files, or a missing/corrupt BIOS BCD store to FIX-004, where the exact active system volume and rollback image can be established.
Stop if the active system volume is ambiguous, other internal disks cannot be safely isolated, or byte-for-byte system-partition/disk rollback is unavailable before a boot-code write.

Branch E — The SYSTEM hive is explicitly missing or corrupt

Route the exact 0xc000014c, 0xc0000218, or named SYSTEM-hive failure to FIX-017.
From WinRE, select Troubleshoot > Advanced options > System Restore and choose a restore point created before the first failed boot.
If no usable restore point exists, restore a verified system image or verified offline SYSTEM-hive backup made from this installation.
Do not assume W:\Windows\System32\Config\RegBack\SYSTEM is a usable backup. Windows 10 version 1803 and later do not automatically maintain populated RegBack hive copies by default.
If the current and backup hive sizes, dates, and provenance cannot be verified, stop rather than replacing the hive.

Branch F — A stable volume has demonstrated logical file-system errors

Route demonstrated volume/file-system corruption to FIX-016.
Do not run a corrective CHKDSK from this symptom router. FIX-016 first separates logical corruption from device instability, establishes backup, and applies the appropriate repair level.
After FIX-016 reports a stable readable volume, return to the matching boot-path article only if a separate boot-file error remains.

Branch G — Route the exact demonstrated boot mechanism

Wrong boot target or No bootable device: FIX-005.
Missing UEFI Windows Boot Manager entry with otherwise valid files: FIX-003.
Missing/corrupt BCD or 0xc000000f: FIX-004.
0xc000000e, 0xc0000225, or A required device isn't connected or can't be accessed: FIX-004.
0xc0000098 or invalid operating-system information in BCD: FIX-004.
Missing, corrupt, or incorrectly referenced winload.efi: FIX-013.
Demonstrated volume/file-system corruption: FIX-016.
0xc000014c, 0xc0000218, or a missing/corrupt SYSTEM hive: FIX-017.

Verify the result

The machine cold-starts twice without a blinking cursor or manual boot-menu selection.
The intended Windows Boot Manager entry points to the intended disk.
The Windows logo appears and startup reaches sign-in.
The BCD store enumerates without error and its Windows loader points to the detected Windows volume.
The disk remains consistently visible with the expected model and capacity.
No new recovery code, file-system error, or registry-hive error appears.
Windows Boot Manager starts Windows from the one-time menu: Correct the persistent firmware order; do not rebuild Windows boot files.
BCDBoot reports that boot files were successfully created and Windows starts: The existing system partition or its BCD/boot files were incomplete or invalid.
BCDBoot succeeds but the cursor remains: Confirm that firmware is using the repaired ESP or system partition. Multiple internal ESPs or disks can make a successful command target the wrong path.
The code changes to 0xc000014c or 0xc0000218: The boot path progressed to a registry-hive failure. Use System Restore or a verified hive/image backup.
The disk or volume disappears, returns read errors, or changes reported capacity: Stop boot repair and protect the data; this is not a BCD-only failure.
The Windows logo or spinning dots now appear but startup stalls: The loader-phase problem is repaired. Continue with the new kernel/driver-stage symptom instead of repeating BCDBoot.

Undo the change if needed

The following commands are BCD-only rollback. They do not restore other boot files replaced by BCDBoot or an NVRAM entry. This router does not execute MBR or boot-sector writes.

For UEFI/GPT, copy the saved BCD back only if the manual BCDBoot result made startup worse and the saved store is readable:

copy /y W:\BootRepairBackup\BCD-before-blinking-cursor S:\EFI\Microsoft\Boot\BCD

For BIOS/MBR:

copy /y W:\BootRepairBackup\BCD-before-blinking-cursor S:\Boot\BCD

Restore the recorded firmware boot order if it was changed. If byte-for-byte rollback may be required, capture a verified image of the ESP/system partition or whole disk before any dedicated article replaces boot files or writes boot code. Restore that image to reverse those writes. Restore a saved SYSTEM hive only from WinRE and only when its provenance and readability have been verified.

Displayed identifier	Windows name or exact message	When it can apply
No numeric code	Black screen with blinking cursor, blinking underscore before Windows logo	Primary visual symptom. It narrows the startup phase but does not identify which boot component failed.
`0xc000000e`	`STATUS_NO_SUCH_DEVICE` / A required device isn't connected or can't be accessed	Boot Manager or BCD refers to a device that is absent or cannot be opened.
`0xc000000f`	`STATUS_NO_SUCH_FILE` / The Boot Configuration Data for your PC is missing or contains errors	The BCD store, loader, or another required boot file is missing or cannot be read.
`0xc0000225`	`STATUS_NOT_FOUND` / A required device isn't connected or can't be accessed	A required boot object, device, or file cannot be resolved.
`0xc0000098`	`STATUS_FILE_INVALID` / The Boot Configuration Data file doesn't contain valid information for an operating system	The BCD store exists but lacks a valid Windows loader entry or contains invalid data.
`0xc0000034`	`STATUS_OBJECT_NAME_NOT_FOUND`	A named boot object or path is absent. Record the complete file or path shown with the code.
`0xc000014c`	`STATUS_REGISTRY_CORRUPT` / registry file is missing or contains errors	The loader reached the offline registry and could not use it. BCD repair alone will not repair the hive.
`0xc0000218`	`STATUS_CANNOT_LOAD_REGISTRY_FILE` / The operating system couldn't be loaded because the system registry file is missing or contains errors	The SYSTEM hive or another required registry hive is missing, corrupt, or unreadable.
No numeric code	Missing operating system	Exact legacy boot message indicating that no usable operating-system loader was found through the selected BIOS path.
No numeric code	BOOTMGR is missing	Exact Windows legacy boot-manager message.
No numeric code	Search phrases: Boot Configuration Data (BCD) missing or corrupted, Boot file or MBR corrupted, Boot sector missing or corrupted, Unable to boot due to system hive missing or corrupted	Microsoft diagnostic categories and useful search phrases; they are not guaranteed to appear verbatim on the screen.