Unison unable to connect due to missing prf file

I can SSH into the remote machine. I have the remote machine mounted as a folder in Nautilus. I have the same version of Unison installed on both my local and remote machine. However, Unison is unable to connect to the target machine via SSH or "Local", complaining:

    Uncaught exception Sys_error("/home/myuser/.unison/myuser@remotehost/home/myuser.prf: No such file or directory")'

This error message is completely unhelpful and doesn't explain why this file would be needed, nor how I should create it.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unison 2.40.102-2ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-31.36~14.04.1-generic 3.19.8-ckt7
Uname: Linux 3.19.0-31-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.16
Architecture: amd64
Date: Fri Oct 30 22:43:51 2015
Dependencies:
 gcc-4.9-base 4.9.1-0ubuntu1
 libc6 2.19-0ubuntu6.6
 libgcc1 1:4.9.1-0ubuntu1
 multiarch-support 2.19-0ubuntu6.6
InstallationDate: Installed on 2015-10-20 (10 days ago)
InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
SourcePackage: unison
UpgradeStatus: No upgrade log present (probably fresh install)