Time Machine stuck at Stopping

Recently upgraded my DS1812+ memory, the backup job was stuck, but I don't know whether they are related. Because I was rebooting in the morning, but the backup was stuck at 4pm.

Fix

To fix the issue, run following command

sudo killall backupd

Some people mentioned commands

sudo service com.apple.metadata.mds stop
sudo service com.apple.metadata.mds start

But there is no service command in my MacOS.

References

10.5: How to abort a stuck Time Machine backup