After upgrade to 21.04, Software Update Issue : ubuntu "security update" package failed

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After I upgraded from Ubuntu 20.10 to 21.04, updates kept returning the error message "ubuntu "security update"package failed."  After going through a long list of google search results, and trying mostly useless stuff, I came upon this solution at this location.  Be sure to note that I added a cd command (see below) to the instructions at the referenced location.

Before you apply the solution below, borrowed from the location link above, be aware that my research and my many attempts at correcting this problem from the Terminal turned up one crucial, common phrase, which is: 

dpkg: error processing usrmerge package (--configure): 

I don't know what a usrmerge package is, but all I know is that whatever it is it got sideways of my 

software updater after I did the upgrade. If you are trying fixes and don't see "usrmerge package" somewhere in your Terminal error messages OR in suggested solutions in forums, you probably don't have the same problem I had. 

SOLUTION: (Note: I added the third line, cd, to the instructions found in the link above, as it might
not be obvious to some that the last (install) command should be executed in the base directory and not
in the .../info directory.)

cd /var/lib/dpkg/info
sudo rm usrmerge.*
cd
sudo apt-get -f install