When critical Windows system files are missing or corrupted, your operating system may begin to malfunction. Common symptoms include Windows features not working properly, system errors, or Windows becoming unresponsive or freezing.

This update is for Windows 8.1 out-of-box experience (OOBE). This update lets you start an immediate free upgrade to Windows 10 during the Windows 8.1 OOBE process.

This update allows Windows desktop applications that depend on the Windows 10 Universal CRT release to run on earlier Windows operating systems. Microsoft Visual Studio 2015 creates a dependency on the Universal CRT when applications are built by using the Windows 10 Software Development Kit (SDK).

Start your device from the USB drive that was created with Recovery Drive. The process to boot from a USB drive may vary by manufacturer, so refer to your device's manual if needed. Create a recovery drive to reinstall Windows in case you experience a major issue such as hardware failure.

Use this tool to find and remove specific prevalent threats and reverse the changes that they made (see Covered malware families). For comprehensive malware detection and removal, consider using Windows Defender Offline or Microsoft Safety Scanner.

Note If the auto detection result is not displayed on your screen, view How to determine whether a computer is running a 32-bit version or 64-bit version of the Windows operation system.

The protected-mode version of the Windows Registry Checker tool (Scanregw.exe) can create a backup of the system files and scan the registry for invalid entries.

Get answers to some common questions about 32-bit and 64-bit versions of Windows.

Check if the module is compatible with an x86 (32-bit) or x64 (64-bit) version of regsvr32.exe.

No. Support for Windows 8.1 is discontinued, but the software will continue to function. However, after January 10, 2023, your computer running Windows 8.1 will no longer receive security updates.