Blue screen in Windows: what it means and what to do

This guide is for anyone whose computer suddenly showed a blue screen, or a black one, and restarted itself. You will learn how to read what is on the screen, what to try on your own and in what order, and how to tell when the problem is in the hardware.

What is a blue screen, really?

A blue screen is an emergency stop by Windows. When a component in the core of the system, usually a driver or the hardware itself, does something the system cannot safely continue from, Windows stops everything to avoid damaging your data and restarts the computer.

Microsoft calls this a stop code error. The screen shows the sentence “Your device ran into a problem and needs to restart”. It is not a virus and not a “computer crash” in the sense of damage. It is a message that something went wrong.

Why is my screen black and not blue?

Because Microsoft changed the design in 2025. In June 2025 the company announced a simpler screen on a black background, and it reached every computer running Windows 11 version 24H2 and later in the summer 2025 updates. Microsoft’s official support page on stop code errors shows both designs: black for version 24H2 and later, and the familiar blue screen for version 23H2 and earlier.

What actually changed: there is no more sad face, and according to reports on the new design there is no QR code either. The two important things remain: the stop code, and sometimes the name of the file that caused the crash. In Windows 10 and in older versions of Windows 11 the screen is still blue, and sometimes it has a QR code that leads to a general support page. It does not diagnose your computer.

What does the code on the screen mean?

The stop code is an English word in capital letters with underscores, for example MEMORY_MANAGEMENT. It points in a direction, not at the final culprit.

The first thing worth doing: take a photo of the screen with your phone. If a file name ending in .sys appears as well, it is especially important. That is usually the driver that crashed. Searching for the name on Google will tell you which component it belongs to. For example, nvlddmkm.sys belongs to the driver for NVIDIA graphics cards.

While the screen is showing, Windows saves a file with the crash details and shows the progress as a percentage. Do not turn off the computer in the middle if you can wait. That file helps a technician understand what happened, even after the screen is gone. In the new design, a hexadecimal number (for example 0x0000001A) appears next to the code name, and you can search for that too.

Decision table: code, cause and what to do

A blue screen once: should you worry?

In most cases, no. A single screen after an update, after connecting new equipment or in the middle of an installation can be a one-time event. Write down the code and keep working. If it does not come back within a few days, there is nothing to do.

The sign that it is no longer a one-time event: the same code comes back, or the crashes appear every time you do a specific thing, such as gaming, printing or connecting a device.

What do you do if the blue screen keeps coming back?

Work from the simple to the complicated. After each step, check whether the crashes have stopped:

1. Disconnect new equipment. Anything you connected or installed before the crashes started: a printer, a camera, a card, memory. This is also the first step Microsoft recommends.
2. Check Device Manager. Right-click Start and choose Device Manager. A device with a yellow exclamation mark is a suspect. Update it, or in its properties choose Roll Back Driver if the problem started after one of its updates.
3. Remove the latest update. In Settings > Windows Update > Update history > Uninstall updates you can remove an update that was installed right before the crashes started.
4. Test the memory. Type mdsched in the Start menu and open Windows Memory Diagnostic. The computer will restart and test the memory. A single error in the test is enough to suspect the memory module.
5. Repair system files. Right-click Start, choose Terminal (Admin) and run sfc /scannow. If it reports that it could not repair everything, run DISM /Online /Cleanup-Image /RestoreHealth and then sfc again.
6. Make sure there is free space. Microsoft recommends keeping 10 to 15 percent of the disk free.
7. Take the system back to an earlier point. System Restore returns settings, drivers and programs to a point in time when everything worked, without touching your documents and photos.

How do you get into Safe Mode when Windows will not boot?

Through the Windows Recovery Environment, a light blue screen with the heading Choose an option. If Windows fails to boot several times in a row, it enters this environment on its own. You can also force it: turn on the computer, and as soon as the logo appears, hold the power button for about ten seconds until the computer shuts off. After two of those, on the third start Windows should boot into the recovery environment, according to Microsoft.

From there the path to Safe Mode is:

1. Troubleshoot > Advanced options > Startup Settings > Restart.
2. On the screen that appears, press 4 or F4 for Safe Mode, or 5 or F5 for Safe Mode with Networking. The details are in Microsoft’s guide to Startup Settings.

In Safe Mode, Windows boots with only the basic drivers. If the computer is stable there, the problem is almost certainly in a driver or a program, not in the hardware. From the same environment you can also remove updates and run System Restore. If Windows does not reach the desktop at all, continue to the guide on a computer that turns on but Windows will not boot.

When does a blue screen mean a hardware problem?

When the crashes continue even after you have ruled out the software. The clear signs:

• Different codes on every crash, with no obvious link to a specific action.
• The crashes appear in Safe Mode too.
• The memory test finds errors.
• The crashes happen under load or when the computer is hot.
• Disk codes, together with slowness or clicking. In that case, read the guide on a hard drive that clicks.
• A clean install of Windows did not help.

What not to do?

• Do not download “blue screen fixers” or driver update programs from unfamiliar websites. Drivers come from Windows Update or the manufacturer’s website only.
• Do not format before backing up. If the computer still boots, back up now. The backup guide explains how.
• Do not keep turning on, again and again, a computer whose disk is clicking. Every start can make the damage worse.
• Do not call a phone number that appears in an “error” window in the browser. A real blue screen never includes a phone number, and a window like that is a scam attempt. How to recognize it, and what to do if you already called, is explained in the guide on fake virus warnings.

When to bring the computer to the lab

When the table above says “Yes” or “Immediately”. When the memory test found errors. When the crashes come back in Safe Mode too, or after a clean install. And when there are signs of a failing disk that holds files with no backup. In that case it is better to start with data recovery from the disk before any other repair. There is no promise that everything, or even part of it, will be recovered, but the odds are better when nobody has worked on the disk first.

If it turns out the problem is in the software and not the hardware, sometimes a clean installation of Windows is the most stable solution, after a backup.

Did it not work out?

The goal is for you to understand what the computer is trying to tell you and solve it on your own. If the screen keeps coming back, we will diagnose whether it is a driver, memory, the disk or something else, and you will get a price before any work begins. You can start from the computer repair page.