deja-dup failing with gpg read errors

[Wim Lewis]

Starting a couple weeks ago, backups have begun failing with the following message. Until now, I have had no problems with backups; I backup via ssh to a cloud provider. (Until ~6 months ago I was backing up via ssh to a machine on my local net.) The scheduled backup asks for my ssh key passphrase and backup encryption passphrase as normal, but a few minutes later this error is displayed. The mounted ssh filesystem is visible in Nautilus and looks normal to me.

GPGError: GPG Failed, see log below:
===== Begin GnuPG log =====
gpg: WARNING: "--no-use-agent" is an obsolete option - it has no effect
gpg: AES256 encrypted data
gpg: encrypted with 1 passphrase
gpg: block_filter 0x0000562ce7e1c020: read error (size=16008,a->size=16008)
gpg: block_filter 0x0000562ce7e1ccc0: read error (size=15992,a->size=15992)
gpg: WARNING: message was not integrity protected
gpg: block_filter: pending bytes!
gpg: block_filter: pending bytes!
===== End GnuPG log =====

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: deja-dup 40.1-1ubuntu2
ProcVersionSignature: Ubuntu 5.3.0-53.47-generic 5.3.18
Uname: Linux 5.3.0-53-generic x86_64
ApportVersion: 2.20.11-0ubuntu8.8
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Wed May 27 00:27:14 2020
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-trusty-amd64-osp1-20150720-0
ExecutablePath: /usr/bin/deja-dup
InstallationDate: Installed on 2016-04-15 (1503 days ago)
InstallationMedia: Ubuntu 14.04 "Trusty" - Build amd64 LIVE Binary 20150720-04:06
SourcePackage: deja-dup
UpgradeStatus: Upgraded to eoan on 2020-01-01 (147 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Wim Lewis (wiml)]

I did eventually resolve this by deleting a corrupt file in (I think) ~/.cache/deja-dup , although it was difficult to figure out what needed to go.