'Failed unmounting /run/user/1000' error on shutdown & reboot

When I shutdown or reboot my computer, it gives me the error message ‘Failed unmounting /run/user/1000.’ I don’t know why it’s happening and when it started showing the error. I don’t know what /run/user/1000 is.
I have made attempts to research about the issue and found no solutions for my problem. If you have a solution to my issue, please let me know!

You might be running stuff that isn’t terminated properly, but don’t worry because /run is a tmpfs that only exists in memory and /run/user/1000 is remade each time your user session is started.