I had a rather odd error with OctopusDeploy where the RavenDB backups were failing. Turns out the problem was because I had assigned 1 IPv4 address to OctopusDeploy and another IPv4 address for TeamCity. Oddly the RavenDB backup routine referenced the localhost address – 127.0.0.1, it appeared to be hardcode with no option other then changing port. This was especially weird as the OctopusDeploy service, was able to access it fine. To resolve – at least long enough to get a backup to migrate to v3 which uses SQL Server – was to setup a port proxy so accessing TCP port 10931 on the local loopback would resolve to the same port but on a the actual public IPv4
To do this run Command Prompt as Administrator (right-click, Run As Administrator) then type
netsh
interface portproxy
add v4tov4 listenaddress=127.0.0.1 listenport=10931 connectaddress={{your ip}} connectport=10931
Remember to replace {{your ip}} with the actual IP address