I decided to install VMware's VDP, went to MyVMware.com and downloaded it. I was presented with the option to download v5.8. So download the OVA, installed, configured, and did a few backups.
Then it was decided to upgrade the vCenter Appliance, from 5.5u1 to 5.5u3. The compatibility matrix said all was good. After the vCenter upgrade, VPD would not work any more. "An attempt made to backup a client failed because no data was found that matches the type of data the job was configured for." Turns out VDP v5.8 isn't compatible with vCenter u3.
Uggg... Okay let's upgrade VDP, but MyVMware.com doesn't list a newer version. Googling for it however yields that v6.1 out, and gives links to downloads.
Ok, download the latest and greatest v6.1.2. Note to do an inplace upgrade, one must download the ISO, attach it to the VDP appliance. Also note one must also make a VMware snapshot before the upgrade. When launching the update process it just sat there forever spinning its wheels. Turns out that one cannot upgrade to v6.1.x; the version of SUSE Linux it is built on had a major version shift and there isn't an inplace upgrade. So download the 6.0.2 ISO, attach, upgrade.
After upgrading to VDP v18.104.22.168 I still have the same error message. Still working on this...