xtrabackup: This target seems to be not prepared . my backup has completed

I run backups early in the morning. However I’ve noticed the backups complete yet. I am unsure why the backup completes but then it shuts itself down.
Here is my backup script
dest=“current_backup/”;
xtrabackup --backup --target-dir=$dest --no-timestamp 2> $log;
xtrabackup --prepare --target-dir=$dest 2>> $log;

My log when the backup happens.

91211 02:14:00 [00] Copying ib_buffer_pool to /db_backup/current_backup/ib_buffer_pool
191211 02:14:00 [00] …done
191211 02:14:00 Backup created in directory ‘/db_backup/current_backup/’
191211 02:14:00 [00] Writing /db_backup/current_backup/backup-my.cnf
191211 02:14:00 [00] …done
191211 02:14:00 [00] Writing /db_backup/current_backup/xtrabackup_info
191211 02:14:00 [00] …done
xtrabackup: Transaction log of lsn (5385754852588) to (5385817296328) was copied.
191211 02:14:01 completed OK!
xtrabackup version 2.4.9 based on MySQL server 5.7.13 Linux (x86_64) (revision id: a467167cdd4)
xtrabackup: cd to /db_backup/current_backup/
xtrabackup: This target seems to be not prepared yet.
InnoDB: Number of pools: 1
xtrabackup: xtrabackup_logfile detected: size=70254592, start_lsn=(5385754852588)
xtrabackup: using the following InnoDB configuration for recovery:
xtrabackup: innodb_data_home_dir = .
xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend
xtrabackup: innodb_log_group_home_dir = .
xtrabackup: innodb_log_files_in_group = 1
xtrabackup: innodb_log_file_size = 70254592
xtrabackup: using the following InnoDB configuration for recovery:
xtrabackup: innodb_data_home_dir = .
xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend
xtrabackup: innodb_log_group_home_dir = .
xtrabackup: innodb_log_file_size = 70254592
xtrabackup: Starting InnoDB instance for recovery.
xtrabackup: Using 104857600 bytes for buffer pool (set by --use-memory parameter)
InnoDB: PUNCH HOLE support available

Doing recovery: scanned up to log sequence number 5385817296328
InnoDB: Database was not shutdown normally!
InnoDB: Starting crash recovery.
InnoDB: Doing recovery: scanned up to log sequence number 5385817296328 (99%)
page_cleaner: 1000ms intended loop took 530588ms. The settings might not be optimal
starting shutdown with innodb_fast_shutdown = 1
Starting shutdown…
Shutdown completed.

Here is my.cnf
sql_mode = STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
innodb_buffer_pool_size = 25G
innodb_buffer_pool_instances = 8
innodb_lock_wait_timeout = 3600000
wait_timeout = 86400
interactive_timeout = 86400
max_heap_table_size = 96M
sort_buffer_size = 16M
join_buffer_size = 16M
tmp_table_size = 96M
max_sort_length = 8K
max_allowed_packet = 16M
group_concat_max_len = 16M
max_connections = 200
max_connect_errors = 10
expire_logs_days = 2
max_binlog_size = 128M

symbolic-links=0
log-bin=binlog
binlog-format=ROW
log_slave_updates
wsrep_log_conflicts
expire_logs_days=7