How to Fix Error Code 1921?
Basically, when you try to install or update Microsoft Office returns you with this Error code 1921. Many users reported that they encountered this Error message “ERROR 1921: Service ‘MDM’.

In this scenario, verify if you have sufficient admin privileges to stop the system services.

Error 1921 is a general problem for the Windows system. It will stop you from being able to install “Microsoft Office” and different programs on your computer.

It has a debugging feature which is known as “Microsoft Debug Manager”https://www.officelivesupport.....com/fix-error-code-1