Error 1921 is a common problem for Windows computers, as it will continually prevent you from installing “Microsoft Office” and a variety of other programs on your system. The error is basically caused by the “Machine Debug Manager” it runs automatically on your system, preventing its installer from running properly. The way to resolve this error is to stop the execution of this service, as well as correct any of the possible Windows errors that may be causing the error to be displayed.

The way error 1921 will normally show up in this format when you try to install a program on your PC:

  • ERROR 1921
  • The ‘MDM’ service could not be stopped. Verify that you have sufficient privileges to stop system services.

The error you are seeing basically means that when your PC tries to install your software, it is holding up because it cannot stop a particular service from running. Windows has a large number of “services” running continuously on your system, allowing Windows to perform a number of different activities, such as maintaining your Internet connection and keeping the “Start menu” running. Although Windows services are necessary for your PC to function, they are continually causing you many problems that need to be fixed.

The first step in correcting error 1921 is to stop the “Machine Debug Manager” service from running. This is easily done by clicking Start> Control Panel> Administrator Tools> Services. Clicking this option will load a screen with the various services your computer is running. Through the list you have, you need to find the “Machine Debug Manager” and stop it from running. This will allow your installation to begin.

The second step in correcting the 1921 error is actually the most important, because it is where you fix the various settings that might have caused the error in the first place. The problem that actually causes the error could be due to a part of your system called the “registry,” which is a central directory of information and settings that Windows uses to run. Although the registry is continually used to help your computer run as smoothly as possible, it is also one of the most harmful parts of your system, causing Windows to continually display various errors. To prevent error 1921 from happening again, it is recommended that you use a registry cleaner to scan your PC’s registry database and correct any errors you have.