What is DefMgr.exe?

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the DefMgr.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

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DefMgr.exe file information

Windows Task Manager with DefMgr
DefMgr.exe process in Windows Task Manager

The process known as Microsoft Default Manager or WinFX Runtime Components belongs to software Default Manager or Microsoft Default Manager or Windows Internet Explorer by Microsoft (

Description: DefMgr.exe is not essential for the Windows OS and causes relatively few problems. DefMgr.exe is located in a subfolder of "C:\Program Files". Known file sizes on Windows 10/8/7/XP are 288,088 bytes (33% of all occurrences), 439,568 bytes and 5 more variants. 
It is not a Windows system file. The file has a digital signature. The application is loaded during the Windows boot process (see Registry key: MACHINE\Run). The program has a visible window. The software can be removed using the Control Panel's Add\Remove programs applet. Therefore the technical security rating is 5% dangerous.

Uninstalling this variant: The developer MSN provides a support site for assistance, and an uninstaller (Control Panel ⇒ Uninstall a Program ⇒ Microsoft Default Manager or Default Manager).

Recommended: Identify DefMgr.exe related errors

If DefMgr.exe is located in the C:\Windows\System32\drivers folder, the security rating is 76% dangerous. The file size is 104,448 bytes. The program is not visible. DefMgr.exe is located in the Windows folder, but it is not a Windows core file. The process is loaded during the Windows boot process (see Registry key: MACHINE\Run). DefMgr.exe is not a Windows system file. The process listens for or sends data on open ports to a LAN or the Internet. DefMgr.exe is able to monitor applications.

Important: Some malware camouflages itself as DefMgr.exe, particularly when located in the C:\Windows or C:\Windows\System32 folder. Therefore, you should check the DefMgr.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


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Best practices for resolving DefMgr issues

A clean and tidy computer is the key requirement for avoiding problems with DefMgr. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the DefMgr.exe process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

DefMgr.exe [all]