Trying to upload to Imgur as guest fails

[Palm__]

How to reproduce:

Take a screenshot, click Export then on the Public hosting tab, choose Imgur Guest. Then click Upload

Release:
Description: Ubuntu 16.04.1 LTS
Release: 16.04

Package version:
Installed: 0.93.1-1ubuntu1

When doing the steps above, I get an error instead of the image uploading

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: shutter 0.93.1-1ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Sep 2 16:10:02 2016
InstallationDate: Installed on 2016-08-24 (9 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: shutter
UpgradeStatus: No upgrade log present (probably fresh install)