KeyError: 'pecynnau'

When installing ttf-mscorefonts-installer on Ubuntu 20.04 (using docker image asp-net-6.0-focal)

apt-get update && apt-get -y install ttf-mscorefonts-installer

Error message:

Traceback (most recent call last):
  File "/usr/lib/update-notifier/package-data-downloader", line 351, in <module>
    process_download_requests()
  File "/usr/lib/update-notifier/package-data-downloader", line 329, in process_download_requests
    trigger_update_notifier(previous_failures, permanent=True)
  File "/usr/lib/update-notifier/package-data-downloader", line 156, in trigger_update_notifier
    string.Template(input).substitute(
  File "/usr/lib/python3.8/string.py", line 126, in substitute
    return self.pattern.sub(convert, self.template)
  File "/usr/lib/python3.8/string.py", line 119, in convert
    return str(mapping[named])
KeyError: 'pecynnau'
dpkg: error processing package update-notifier-common (--configure):
 installed update-notifier-common package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of ttf-mscorefonts-installer:
 ttf-mscorefonts-installer depends on update-notifier-common (>= 0.119ubuntu2); however:
  Package update-notifier-common is not configured yet.

dpkg: error processing package ttf-mscorefonts-installer (--configure):
 dependency problems - leaving unconfigured