Error: cannot open ./xtrabackup_checkpoints after I added a new database

After I added a new database to the server, and went back to restoring the backup, I found that there was no mysql folder, and I think because of that, the following error popped up:

191203 11:06:27 innobackupex: Starting the apply-log operation

IMPORTANT: Please check that the apply-log run completes successfully.
At the end of a successful apply-log run innobackupex
prints “completed OK!”.

innobackupex version 2.3.9 based on MySQL server 5.6.24 Linux (x86_64) (revision id: fde0e3e)
xtrabackup: cd to /backup/radius-database-backup/
xtrabackup: Error: cannot open ./xtrabackup_checkpoints
xtrabackup: Error: failed to read metadata from ‘./xtrabackup_checkpoints’