Duplicati Not Launching on Linux (NameResolutionFailure)

[JonMikelV]

Have you tried an nslookup localhost as mentioned here?

Duplicati not launching on Mac OS Sierra 10.12.6

You got it. nslookup localhost failed so I double checked that I had a localhost mapped to 127.0.0.1 in my /etc/hosts, and lo and behold, it was commented out. Not sure why or when that happened - if it was me troubleshooting or maybe some other software package - but adding it in fixed the issue.