After upgrading vCenter to 7.0U3g from 6.7U3p, the VAMI backups have failed. I came across this kb: VAMI Backup with SMB reports error: "Path not exported by the remote filesystem" (86069) (vmware.com...
Does this problem still exist in 7.0U3g?
I was just able to resolve it by appending the username with the UPN.
On vCSA 6.7, the username was specified as "username" and it works fine. On vCSA 7.0, I had to change it to "firstname.lastname@example.org" and that worked. I just ran manual backups on all three successfully.