LP #1736210: Decrypt failed with xtrabackup version 2.4.9

**Reported in Launchpad by Rick last update 07-12-2017 13:04:07

I just upgraded to the newest version of xtrabackup on Centos. I now get a decrypt error:

[root@es01 backup]# xtrabackup --decompress --decrypt=AES256 --encrypt-key-file=/data/config/xtrabackupkey.ini --target-dir=/data/backup/mysql/ --remove-original --parallel=4
xtrabackup version 2.4.9 based on MySQL server 5.7.13 Linux (x86_64) (revision id: a467167cdd4)
171204 18:21:49 [01] decrypting and decompressing ./ibdata1.qp.xbcrypt
171204 18:21:49 [02] decrypting and decompressing ./performance_schema/events_waits_summary_by_host_by_event_name.frm.qp.xbcrypt
171204 18:21:49 [04] decrypting and decompressing ./performance_schema/status_by_host.frm.qp.xbcrypt
171204 18:21:49 [03] decrypting and decompressing ./performance_schema/hosts.frm.qp.xbcrypt
encryption: both encryption key and key file specified.
encryption: both encryption key and key file specified.
encryption: unable to set libgcrypt cipher key - User defined source 1 : Invalid key length
encryption: unable to set libgcrypt cipher key - User defined source 1 : Invalid key length
encryption: both encryption key and key file specified.

I do not use the encrypt-key option, only encrypt-key-file option.

If i change the decrypt command to use encrypt-key=<mykey> option i get the following error:

decrypt: failed to close dest file.
171204 18:28:04 [01] removing ./ibdata1.qp.xbcrypt

The failed to close error is for every removing entry.