How to fix error code 0xc0000242 when Windows will not start

Error code 0xc0000242 appears on a blue Recovery screen when Windows cannot load a driver it needs to start. The screen names the file, and that file is damaged, not the boot configuration. Note the File line, then run Startup Repair and repair the file from the recovery Command Prompt.

Facts checked on 15 October 2026. Steps written for Windows 11 (25H2 and 26H2) and Windows 10 22H2.

What error code 0xc0000242 means at startup

The screen that carries this code is the Windows Recovery screen. Users on Microsoft Q&A and Reddit quote it the same way: "Your PC/Device needs to be repaired. The operating system couldn't be loaded because a critical system driver is missing or contains errors." Under it come a File: line with the path of a .sys driver and Error code: 0xc0000242.

Microsoft's list of NTSTATUS values names the code STATUS_BAD_COMPRESSION_BUFFER, with the text "The specified buffer contains ill-formed data". Put simply: Windows read the driver from the disk and the data did not make sense. Microsoft's startup troubleshooting guide says the Windows OS loader loads the drivers the kernel needs and then starts the kernel, so a damaged driver stops the start right there.

Why 0xc0000242 appears: the causes, most common first

The code says the file is damaged, so the question is what damaged it. In the Microsoft Q&A thread the error came after a 12 year old desktop was unplugged and moved while the desk was cleaned. In other reports the File line names an antivirus driver.

Where the cause is written

The error stops Windows before it can write a crash dump, so look in these places instead:

• The File line on the Recovery screen: take a photo of it. It is the most useful fact you have.
• C:\Windows\System32\Logfiles\Srt\SrtTrail.txt: the log Startup Repair writes in Fix 1. It says what it tested and what it found.
• The SFC result in Fix 2: whether Windows found corrupt files and repaired them.
• Event Viewer > Windows Logs > System: once Windows starts again, look for Disk, Ntfs and Kernel-Power events around the first failed start.

How to fix error code 0xc0000242

Every fix starts from the Windows recovery screen. Fix 1 and Fix 2 repair most Windows drivers. Fix 3 checks the disk, Fix 4 and Fix 5 deal with a driver of another program, Fix 6 is only for the BCD, and Fix 7 is the last resort.

Fix 1. Note the file and run Startup Repair from the recovery screen

20 minutesLow riskEveryone, first. It needs no commands and touches no personal files.

Startup Repair checks the files Windows needs to start and replaces what it can. It runs from the recovery environment, which does not load the damaged driver. A Microsoft Q&A answer to this error starts here.

1. Take a photo of the Recovery screen so you have the exact File: line.
2. Turn the PC on and, while the Windows logo and the spinning dots show, hold the power button for 5 to 10 seconds. Do this twice; the third start opens the recovery screen.
3. If the recovery screen never opens, make a Windows 11 USB drive with the Media Creation Tool on another PC, boot from it and select Repair your computer.
4. Select Troubleshoot > Advanced options > Startup Repair. Step by step: Run Startup Repair
5. Pick your account if asked, wait until it finishes and restart.

Fix 2. Repair the damaged Windows driver with an offline SFC scan

20 to 30 minutesLow riskThe File line names a Windows driver, or Startup Repair could not fix the PC.

SFC compares Windows files with Microsoft's stored copies and replaces a damaged one. Microsoft's startup guide gives the offline form, which works on the installed Windows from the recovery Command Prompt while it is not running.

1. Open Troubleshoot > Advanced options > Command Prompt from the recovery screen.
2. Find the Windows drive letter: type dir C:\Windows, then dir D:\Windows, until one lists the folder. In recovery it is often not C:.
3. Run sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows with that letter in both places.
4. Wait until the scan reaches 100 % and read the result.
5. Type exit, select Continue and see whether Windows starts.

In the recovery Command Prompt (replace C: with your Windows drive):

dir C:\Windows
sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

The online version of this scan, with DISM, is for a Windows that still starts: Run DISM and SFC to repair Windows system files. Run it once more after the PC starts again.

Fix 3. Check the system disk for errors with CHKDSK

30 to 90 minutesLow riskThe PC lost power or was moved, the disk is old or slow, or SFC could not repair the file.

Ill-formed data in a driver file often means the disk returned bad data. CHKDSK repairs the file system and, with /r, finds bad sectors, so the SFC scan in Fix 2 can then write a good copy.

1. Shut the PC down. On a desktop that was moved, check that the disk's data and power cables are pushed in firmly.
2. Open the recovery Command Prompt as in Fix 2 and find the Windows drive letter.
3. Run chkdsk C: /f /r with that letter. The /r pass can take an hour or more on a large disk.
4. Read the result, then run the SFC scan from Fix 2 again.
5. Type exit and select Continue. Step by step: Check a disk for errors (chkdsk)

Fix 4. Start in Safe Mode and remove the program that owns the driver

20 minutesLow riskThe File line names a driver that is not part of Windows, for example aswVmm.sys from an antivirus.

SFC repairs only Windows files, so it cannot fix another maker's driver. Safe Mode starts Windows with a minimal set of drivers; if it starts, you can remove the program and install a fresh copy later.

1. Search the file name on another device to find which program installed it. We could not confirm the owner of every file people report, so check the maker's own site.
2. In the recovery screen, select Troubleshoot > Advanced options > Startup Settings > Restart.
3. After the restart, press 4 for Safe Mode or 5 for Safe Mode with Networking. Step by step: Start Windows or a Mac in Safe Mode
4. If Windows starts, back up your important files first.
5. Open Settings > Apps > Installed apps and uninstall the program. Full method: Uninstall a program or app in Windows
6. Restart normally. Install the newest version from the maker only after Windows starts cleanly.

Fix 5. Return Windows to an earlier state with System Restore

20 minutesRead the warningThe error began after you installed a program, a driver or an update, and System Protection was on.

A restore point brings back the drivers and system files from before the change, including the driver on the File line. Microsoft's startup guide recommends a restore point for a Windows that cannot load its system files.

1. Open the recovery screen as in Fix 1 and select Troubleshoot > Advanced options > System Restore.
2. Pick your account and enter its password.
3. Select a restore point dated before the first failed start, then Next and Finish.
4. Do not turn the PC off while it restores. Step by step: Undo recent changes with System Restore

Fix 6. Rebuild the BCD when the File line says \Boot\BCD

15 minutesLow riskOnly when the Recovery screen names \Boot\BCD instead of a driver file.

The Boot Configuration Data tells the boot manager where Windows is. Microsoft's startup guide rebuilds it with bootrec after saving a copy, which is the right repair when this file and not a driver is damaged.

1. Open the recovery Command Prompt as in Fix 2.
2. Run bootrec /ScanOS and restart once to see whether that alone helps.
3. If not, run the four commands below one by one, answering Y when bootrec asks to add the Windows installation.
4. Type exit and select Continue.

From Microsoft's startup troubleshooting guide (on a UEFI PC the BCD lives on the EFI partition, so Startup Repair in Fix 1 is the easier route):

bcdedit /export c:\bcdbackup
attrib c:\boot\bcd -r -s -h
ren c:\boot\bcd bcd.old
bootrec /rebuildbcd

Fix 7. Reinstall Windows and keep your files

60 to 90 minutesRead the warningEvery fix above failed and CHKDSK found the disk healthy.

A reinstall writes a fresh copy of every Windows driver and boot file. The Microsoft Q&A answer to this error ends with Reset this PC, which can keep your personal files.

1. In the recovery screen, select Troubleshoot > Reset this PC > Keep my files.
2. Choose Cloud download for fresh files from Microsoft, or Local reinstall.
3. If the reset cannot start, boot from the Windows USB drive from Fix 1 and install Windows from there.
4. After the reinstall, install the chipset and storage drivers from your PC maker first. Full method: Reinstall Windows without losing files

It didn't work: when 0xc0000242 keeps coming back

If every fix ran and the Recovery screen returns, or it returns days after a repair, the disk is the most likely cause. A disk that returns bad data damages whatever file Windows reads next, so the file name often changes.

• Copy your files off the disk now, before more repairs write to it.
• Test the disk with its maker's tool from another PC, and test the memory with How to test your RAM with Windows Memory Diagnostic once Windows starts.
• Note the exact File line, the code, your PC model and the disk model, and what happened before the first failure.
• Keep the text of SrtTrail.txt from Fix 1 and the SFC and CHKDSK results from Fix 2 and Fix 3.

How to keep 0xc0000242 from coming back

Windows 10 left support on 14 October 2025. A Windows 10 PC gets fixes for drivers and startup only through Extended Security Updates, so moving to Windows 11 keeps them coming.

Frequently asked questions

What is error code 0xc0000242?

It is a Windows status code that Microsoft names STATUS_BAD_COMPRESSION_BUFFER: the specified buffer contains ill-formed data. At startup it means Windows read a driver file from the disk and the data was damaged, so it stopped and showed the Recovery screen. The file is named on the File line just above the code. Fix that one file and Windows usually starts again.

Is 0xc0000242 a Boot BCD error?

Usually not. Many guides call it a Boot BCD error, but the screens users report name a driver file such as mountmgr.sys, SgrmAgent.sys or aswVmm.sys, not the Boot Configuration Data. Rebuilding the BCD does not repair a driver file. Only if the File line says \Boot\BCD should you rebuild it, as Fix 6 shows.

Do I lose my files with error 0xc0000242?

Usually not. The error stops Windows from loading one driver, but your documents and photos are normally still on the disk. Fixes 1 to 4 and Fix 6 do not touch personal files. System Restore removes only apps and drivers installed after the restore point, and Reset this PC with Keep my files keeps personal files. If CHKDSK reports bad sectors, copy your files off before anything else.

Why did 0xc0000242 appear after I moved or unplugged my PC?

In the Microsoft Q&A thread the error appeared right after a user unplugged everything to clean the desk. A desktop that loses power while running, or a disk cable that moves, can leave a driver file half written or make the disk return bad data. Check the cables, then run CHKDSK (Fix 3) and the offline SFC scan (Fix 2).

The File line names aswVmm.sys or another non-Windows file. What now?

Then the damaged driver belongs to another program, and SFC cannot repair it because it only knows Windows files. Users link aswVmm.sys to Avast antivirus; we could not confirm every file name on the makers' sites. Start in Safe Mode, uninstall that program and install a fresh copy from its maker later (Fix 4). If Safe Mode fails too, use System Restore (Fix 5).

Does 0xc0000242 happen on Windows 11 and Windows 10?

Yes. Both use the same OS loader and the same Recovery screen, so the message, the code and the fixes are the same. Newer Windows 11 builds may show Quick machine recovery on the recovery screen, but Startup Repair, Command Prompt, Startup Settings and System Restore are still under Advanced options. Windows 10 left support on 14 October 2025.

I cannot reach the recovery screen. How do I start the fixes?

Interrupt the start twice: while the Windows logo and the spinning dots show, hold the power button for 5 to 10 seconds. On the third start Windows should open the recovery screen. If it does not, make a Windows 11 USB drive with the Media Creation Tool on another PC, boot from it with the boot menu key and select Repair your computer.

Startup Repair said it couldn't repair my PC. What next?

Look at the File line again. If it is a Windows driver, run the offline SFC scan from the recovery Command Prompt (Fix 2), and if SFC fails, run CHKDSK (Fix 3) and then SFC again. If it is another program's driver, go to Safe Mode (Fix 4). The log at C:\Windows\System32\Logfiles\Srt\SrtTrail.txt says what Startup Repair found.

I searched это что or اي الحل for this code. What is the solution?

This page is about the Windows startup error 0xc0000242, which shows Your PC/Device needs to be repaired with a driver file name. The solution in short: note the file on the screen, run Startup Repair from the recovery screen, then repair Windows files with an offline SFC scan. The page is in English; a browser's translate feature can show it in Russian or Arabic.