Configuring VAMI backup of vCenter server using sftp protocol fails with "General system error reported by backup server"

Products

• VMware vCenter Server
• VMware vCenter Server 7.0

Issue/Introduction

• Configuring vCenter Server Appliance Management (VAMI) based backup of vCenter Server using sftp protocol fails with "General system error reported by backup server"

• Issue is seen for sftp based backup with Linux based Guest OS as target server
• This issue is specific to vCenter Server 7.0 and is not seen with version 8.0 U2b and later
• /var/log/vmware/applmgmt/applmgmt.log:

YYYY-MM-DDTHH:MM:SS [19614]INFO:plugins.SftpStorageIOLib:Executing command to get remote root: ssh -q -p 22 -i /root/.ssh/id_rsa -o UserKnownHostsFile=/etc/applmgmt/appliance/br_known_hosts '<backup user>'@'<sftp server IP/FQDN>' echo ~
YYYY-MM-DDTHH:MM:SS [19614]INFO:plugins.SftpStorageIOLib:Authorizing localhost with command sshpass -f /tmp/tmpzvqwhtdz ssh-copy-id -i /root/.ssh/id_rsa.pub -p 22 -o UserKnownHostsFile=/etc/applmgmt/appliance/br_known_hosts <backup user>@<sftp server IP/FQDN>
YYYY-MM-DDTHH:MM:SS [19614]DEBUG:plugins.SftpStorageIOLib:LocalHost authorized
YYYY-MM-DDTHH:MM:SS [19614]INFO:plugins.SftpStorageIOLib:Executing command to get remote root: ssh -q -p 22 -i /root/.ssh/id_rsa -o UserKnownHostsFile=/etc/applmgmt/appliance/br_known_hosts '<backup user>'@'<sftp server IP/FQDN>' echo ~
YYYY-MM-DDTHH:MM:SS [19614]DEBUG:plugins.SftpStorageIOLib:Passwordless ssh tunnel is not working, falling back to CURL
YYYY-MM-DDTHH:MM:SS [19614]ERROR:plugins.FtpStorageIOLib:sftp cmd failed. RC: 2, Err: curl: (2) Failure establishing ssh session: -8, Unable to exchange encryption keys

Cause

This issue is caused due to the version of libssh2 rpm currently installed on vCenter Server 7.0 versions

Resolution

Broadcom is working towards a permanent fix for this issue.

There is no workaround currently available for vCenter Server 7.0

Workaround:

• Proceed to upgrade vCenter server to 8.0 update 2b Build 23319993 or later

OR

• Configure VAMI based backup using a different protocol. Refer to Manually Back up vCenter Server by Using the vCenter Server Management Interface