Yesterday I upgraded my PC to Windows 10 version 1909 from Windows 10 version 1809. Now I have been testing all the Windows 10 version 1909 new features. Microsoft released on feature called Reserved Storage in Windows 10 version 1903. Since I am in Windows 10 version 1909 I am not seeing this feature in the Storage setting. For your reference please check the below image.
Double-click the ShippedWithReserves key, and change it value from 0 to 1 .
Click the OK button.
Once you’ve completed the steps, reboot your computer, and during the next upgrade (build) releases, Windows 10 will set aside hard drive space for updates.
This DISM command has introduced in the Windows 10 version 2004. I assume you are using either Windows 10 version 1903 or Windows 10 version 1909. @Evans this is the reason you are getting the error: 87 in your PC