The blue screen of death (BSoD) or blue screen error, blue screen, fatal error, bugcheck, and officially known as a stop erroris a critical error screen displayed in many iterations of Windows, a series of operating systems by Microsoft. It is used to indicate a system crash, in which the operating system reaches a critical condition where it can no longer operate safely. Its name comes from the blue-colored background used predominantly on the error screens found in the majority of Windows releases, which was changed to black starting with Windows 11 version 24H2.
Possible issues contributing to a BSoD may include hardware failures, an issue with or without a device driver, viruses, malware, and other factors such as intentional user action.
History Initial non-critical error screens
Blue screen errors have been around since the first version of Windows in 1985. In one of the beta versions of Windows 1.0, the boot screen would have the text "Incorrect DOS version" alongside other messages detailing what check failed to pass appended into it if it detects a version of DOS that is newer than the OS expects before starting normally. This behavior remains in the final version released to retail (version 1.01); however, the remaining text messages were removed during development in the lead up to Windows 1.0's release, displaying mojibake instead. This does not indicate a system crash, however, as when the system actually crashes, it usually results in a freeze or the operating system exiting out to DOS. This behavior is also present in Windows 2.0 and Windows 2.1.
Windows 3.0 uses a text-mode screen for displaying important system messages, usually from digital device drivers in 386 Enhanced Mode or other situations where a program could not run. Windows 3.1 changed the color of this screen from black to blue. It also displays a blue screen when the user presses the Ctrl+Alt+Delete key combination to bring up a rudimentary task manager that is reserved for quitting any unresponsive programs if they are available. Like previous versions of Windows, Windows 3.x exits to DOS if an error condition is severe enough.
First critical error screens and contemporary releases
The first BSoD to indicate a critical system error appeared in Windows NT 3.1 (the first version of the Windows NT family, released in 1993) and all subsequent releases. The error screens initially started with *** STOP: in its earlier iterations, hence it became officially known as a "stop error." This format was used on all Windows operating systems released afterwards, with various differences in later versions. Despite popular belief, there are no known genuine equivalents of a BSoD in the Windows Embedded Compact (formerly known as Windows CE) line of embedded operating systems.
BSoDs can be caused by poorly written device drivers or malfunctioning hardware, such as faulty memory, power supply problems, overheating of components, hardware running beyond its specification limits, or even ACPI compliance issues with the BIOS. In the Windows 9x line of operating systems, incompatible DLLs or bugs in the operating system kernel could also cause BSoDs. Because of the general instability and lack of memory protection in Windows 9x, BSoDs were much more common.
Color change and redesign On June 26, 2025, Microsoft announced that the color of the BSoD would be officially changed to black alongside an overhaul of the design of the screen itself which will be present in Windows 11 version 24H2, saying that the new design will be "easier to navigate unexpected restarts and faster recoveries". This new redesign appeared in later insider builds of Windows 11 version 24H2 as early as February 21, 2025 before it was set as the default on March 28, 2025. Previously, the color change appeared on a few builds of Windows 11 (including the RTM) before reverting to a more different shade of blue in later builds of Windows 11 before February 21, 2025. The announcement was made nearly a year after the 2024 CrowdStrike outages in July 2024 (which caused BSoDs to many computers in the business and enterprise segments running Windows due to an update bug), and the change was made eight months after the incident.
Attribution
In September 2014, Microsoft employee Raymond Chen published a blog post entitled "Who wrote the text for the Ctrl+Alt+Del dialog in Windows 3.1?", which focused on the creation of the first rudimentary task manager in Windows 3.x. Chen reported that Steve Ballmer, the former CEO of Microsoft, had written the text of this message. Because this dialog box has a similar appearance to the Blue Screen of Death, several online journals reporting on his blog post claimed that Chen had attributed the creation of the Blue Screen of Death to Ballmer.
Chen released a clarification in a later blog post, where he criticized the news sites that had picked up on the story. He reported that over half a dozen sites had embellished or invented details in their stories, including incorrectly naming Chen as a Microsoft executive, treating Chen as an "official company spokesperson", and using unrelated images from Windows 95 or Windows NT as illustrations. This was followed up by a further blog post in which Chen claimed responsibility for revising the BSoD in Windows 95, saying that he was the one who "sort of" created the BSoD in its first modern incarnation in Windows 95.
According to former Microsoft employee Dave Plummer, the BSoD in the Windows NT family was not based on the rudimentary task manager screen of Windows 3.x, but was actually designed by Microsoft developer John Vert. Vert has also stated the reason why the error screens were blue was because the universal color palette of the video hardware at that time was very rudimentary and he personally used a MIPS OS box and SlickEdit for programming so that both the firmware and editor displayed white text on a blue background, making it for a more consistent programming experience.
Formats
BSoDs originally showed silver (HTML color #A8A8A8) (and later white (HTML color #FFFFFF)) text on a royal blue (HTML color #0000A8 for Windows NT 3.1–4.0; HTML color #000080 for Windows 2000–7) background with information about current memory values and register values. Starting with Windows Server 2012 (released in September 2012), Windows adopted a cerulean background (HTML color #1A67B3 for Windows 8/8.1 to Windows 10 version 1511; HTML color #0078D7 for Windows 10 version 1607–22H2). Earlier versions of Windows 11 used a black background, which was changed to dark blue starting with build 22000.348 and then back to black with build 26120.3653. Preview builds of Windows 10, Windows 11, and Windows Server (available from the Windows Insider program) feature a dark green (HTML color #246F24) background instead of a blue one. Windows 3.1, 95, and 98 supports customizing the color of the screen whereas the color was hard-coded in the Windows NT family.
Windows 95, 98, and Me render their BSoDs in the 80×25 text mode with a 720×400 screen resolution. BSoDs in the Windows NT family initially used the 80×50 text mode with a 720×400 screen resolution, but were displayed in a 640×480 screen resolution starting with Windows 2000. BSoDs from Windows 8 and Windows Server 2012 onwards are rendered in higher resolutions than previous versions of Windows, specifically the highest screen resolution available on UEFI machines. On legacy BIOS machines, they use the 1024×768 resolution by default, but they can also be configured to use the highest resolution exposed by the firmware (via the highestmode parameter in Boot Configuration Data). Windows 95, 98, Me, and NT versions prior to Windows 2000 used text mode fonts provided by the graphics adapter; Windows 2000, XP, Vista and 7 used kernel mode fonts provided by the kernel's boot video driver bootvid.dll, which is a text mode-like font used in Windows 2000 and Lucida Console in Windows XP to 7. Windows 8 and Windows Server 2012 onwards use the Segoe UI font.
Windows 10 builds 14316 and up uses the same format as Windows 8, but has a QR code which leads to a Microsoft Support web page that tries to help users troubleshoot the issue step-by-step. This format was retained in Windows 11, however build 26120.3291 onwards changes the layout to be more consistent with that of Windows 11's UI, removing the QR code among other changes.
Windows NT
In the Windows NT family of operating systems, the blue screen of death (referred to as "bug check" in the Windows software development kit and driver development kit documentation) occurs when the kernel or a driver running in kernel mode encounters an error from which it cannot recover. This was usually caused by an illegal operation being performed. The only safe action the operating system can take in this situation was to restart the computer. Because of this, data loss may occur since the restart was unplanned, and the user was not given an opportunity to save their work.
The text on the error screen contains the code of the error and its symbolic name (e.g. ) along with four error-dependent values in parentheses that are there to help software engineers fix the problem that occurred. Depending on the error code, it may display the address where the problem occurred, along with the driver which was loaded at that address. Under Windows NT, the second and third sections of the screen may contain information on all loaded drivers and a stack dump, respectively. The driver information was in three columns; the first lists the base address of the driver, the second lists the driver's creation date (as a Unix timestamp), and the third lists the name of the driver. By default, Windows will create a memory dump file when a stop error occurs. Depending on the OS version, there may be several formats this can be saved in, ranging from a 64kB "minidump" (introduced in Windows 2000) to a "complete dump" which was effectively a copy of the entire contents of physical memory (RAM). The resulting memory dump file may be debugged later, using a kernel debugger. For Windows, WinDBG or KD debuggers from Debugging Tools for Windows are used. A debugger was necessary to obtain a stack trace, and may be required to ascertain the true cause of the problem; as the information on-screen was limited and thus possibly misleading, it may hide the true source of the error. By default, Windows XP was configured to save only a 64kB minidump when it encounters a stop error, and to then automatically reboot the computer. Because this process happens very quickly, the blue screen may be seen only for an instant or not at all. Users have sometimes noted this as a random reboot rather than a traditional stop error, and are only aware of an issue after Windows reboots and displays a notification that it has recovered from a serious error. This happens only when the computer has a function called "Auto Restart" enabled, which can be disabled in the Control Panel which in turn shows the stop error.
Microsoft Windows can also be configured to send live debugging information to a kernel debugger running on a separate computer. If a stop error was encountered while a live kernel debugger was attached to the system, Windows will halt execution and cause the debugger to break in, rather than displaying the BSoD. The debugger can then be used to examine the contents of memory and determine the source of the problem.
A BSoD can also be caused by a critical boot loader error, where the operating system was unable to access the boot partition due to incorrect storage drivers, a damaged file system or similar problems. The error code in this situation was . In such cases, there was no memory dump saved. Since the system was unable to boot from the hard drive in this situation, correction of the problem often requires using the repair tools found on the Windows installation disc.
Details
Earlier versions (NT, 2000, XP, Vista, 7)