With ESXi 6.0 U1 (and above), SSLv3 support is disabled by default for all services and ports. If the host was running a version prior to this, this might be the problem. More details in the article KB2063: After applying update 1 for vSphere 6.0, Jobs fail with NFC storage unavailable -
Resolution-1 --> Upgrade Veeam to the latest version.
Resolution-2 --> Enable SSLv3 on all the hosts. Steps as below -
1. Create a backup copy of the /etc/vmware/config file
2. Edit the /etc/vmware/config file to append the following line at the end of the file:
vmauthd.ssl.noSSLv3 = "false"
Note: If you have the line vmauthd.ssl.noSSLv3 = true in the file, change it to vmauthd.ssl.noSSLv3 = false
Example of /etc/vmware/config file:
authd.proxy.vpxa-nfc = "vmware-vpxa:vpxa-nfc"
authd.fullpath = "/sbin/authd"
vmauthd.ssl.noSSLv3 = "false"
3. Restart the rhttpproxy service with the command:
/etc/init.d/rhttpproxy restart
If this does not resolve the issue, share one of the failed VM agent log file from the Veeam proxy VM. It will be under the location <%programdata%\Veeam\Backup>.
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Cheers,
Supreet