QUESTION: How do I delete the corrupted Deja Dup backup to fix this bug?  Which files do I delete?  I see 3 folders in my backup drive:
$RECYCLE.BIN
System Volume Information
thomas-G752VL (my backup folder)
What about deleting ~/.cache/deja-dup/

I also have this bug.  I think it happened when my laptop froze and I forced a shutdown.  Even though I think Deja Dup was not backing up at the time that may have corrupted the backup.

GPGError: GPG Failed, see log below:
===== Begin GnuPG log =====
gpg: no valid OpenPGP data found.
gpg: decrypt_message failed: Unknown system error
===== End GnuPG log =====

1. The distribution of Linux you're using:
Ubuntu 20.04.3 LTS

2. The version of deja-dup and duplicity:
deja-dup	40.7-0ubuntu1
duplicity	0.8.11.1612-1

3. The file /tmp/deja-dup.gsettings after running the following line (you may want to scrub the file of any incriminating file names or details):
org.gnome.DejaDup exclude-list ['$TRASH', '$DOWNLOAD']
org.gnome.DejaDup allow-metered false
org.gnome.DejaDup root-prompt true
org.gnome.DejaDup periodic-period 1
org.gnome.DejaDup include-list ['/home/thomas', '/mnt/M2DATA/VirtualBoxVMs']
org.gnome.DejaDup prompt-check '2020-11-03T15:35:13+00'
org.gnome.DejaDup periodic true
org.gnome.DejaDup delete-after 0
org.gnome.DejaDup last-restore ''
org.gnome.DejaDup last-run '2021-10-06T17:35:36+00'
org.gnome.DejaDup full-backup-period 90
org.gnome.DejaDup last-backup '2021-10-06T17:35:36+00'
org.gnome.DejaDup backend 'drive'
org.gnome.DejaDup nag-check '2021-08-05T03:36:41+00'
org.gnome.DejaDup.S3 folder 'thomas-G752VL'
org.gnome.DejaDup.S3 bucket ''
org.gnome.DejaDup.S3 id ''
org.gnome.DejaDup.Rackspace container 'thomas-G752VL'
org.gnome.DejaDup.Rackspace username ''
org.gnome.DejaDup.OpenStack authurl ''
org.gnome.DejaDup.OpenStack tenant ''
org.gnome.DejaDup.OpenStack container 'thomas-G752VL'
org.gnome.DejaDup.OpenStack username ''
org.gnome.DejaDup.GCS folder 'thomas-G752VL'
org.gnome.DejaDup.GCS bucket ''
org.gnome.DejaDup.GCS id ''
org.gnome.DejaDup.Local folder 'thomas-G752VL'
org.gnome.DejaDup.Google folder 'thomas-G752VL'
org.gnome.DejaDup.GOA folder '$HOSTNAME'
org.gnome.DejaDup.GOA id ''
org.gnome.DejaDup.GOA type ''
org.gnome.DejaDup.GOA migrated false
org.gnome.DejaDup.Drive folder 'thomas-G752VL'
org.gnome.DejaDup.Drive uuid '5AE3-3A3B'
org.gnome.DejaDup.Drive name 'Samsung_T5'
org.gnome.DejaDup.Drive icon '. GThemedIcon drive-harddisk-solidstate-usb drive-harddisk-solidstate drive-harddisk drive drive-harddisk-solidstate-usb-symbolic drive-harddisk-solidstate-symbolic drive-harddisk-symbolic drive-symbolic'
org.gnome.DejaDup.File path ''
org.gnome.DejaDup.File relpath @ay []
org.gnome.DejaDup.File name ''
org.gnome.DejaDup.File migrated true
org.gnome.DejaDup.File type 'normal'
org.gnome.DejaDup.File uuid ''
org.gnome.DejaDup.File short-name ''
org.gnome.DejaDup.File icon ''
org.gnome.DejaDup.Remote folder 'thomas-G752VL'
org.gnome.DejaDup.Remote uri ''

4. The file /tmp/deja-dup.log after running the appropriate line below and replicating the problem (you may want to scrub the log of any incriminating file names or details):

 * If you're having problems backing up:
    DEJA_DUP_DEBUG=1 deja-dup --backup | tail -n 1000 > /tmp/deja-dup.log

Attached deja-dup.log