// To cleanup !

= Date Time format
[[https://support.mozilla.org/en-US/kb/customize-date-time-formats-thunderbird|Customize Date and Time formats in Thunderbird]]

Or this old info?

== Date format trouble

* https://bugzilla.mozilla.org/show_bug.cgi?id=1426907
* https://bugzilla.mozilla.org/show_bug.cgi?id=1509096
* https://bugzilla.mozilla.org/show_bug.cgi?id=1502659
* https://askubuntu.com/questions/214099/how-to-change-thunderbirds-display-time-to-24h-format#comment1593436_217718
* https://gitlab.com/jeff_harp/Thunderbird_60.4.0_date-time_mods
* https://bugzilla.mozilla.org/show_bug.cgi?id=1344594
* https://support.mozilla.org/en-US/questions/1232251

NO Good:

Thunderbird Preferences > Advanced > General > Date and Time Formatting:

Regional settings locale: English (Denmark)

OK:

https://bugzilla.mozilla.org/show_bug.cgi?id=1426907#c59

  $ sudo ln -si /usr/share/i18n/locales/en_DK /usr/share/i18n/locales/root
   [sudo] password for mi:
  $ echo 'root.UTF-8 UTF-8' | sudo tee -a /etc/locale.gen
   root.UTF-8 UTF-8
  $ sudo locale-gen
   Generating locales (this might take a while)...
     de_CH.UTF-8... done
     en_AG.UTF-8... done
     en_AU.UTF-8... done
     en_BW.UTF-8... done
     en_CA.UTF-8... done
     en_DK.UTF-8... done
     en_GB.UTF-8... done
     en_HK.UTF-8... done
     en_IE.UTF-8... done
     en_IN.UTF-8... done
     en_NG.UTF-8... done
     en_NZ.UTF-8... done
     en_PH.UTF-8... done
     en_SG.UTF-8... done
     en_US.UTF-8... done
     en_ZA.UTF-8... done
     en_ZM.UTF-8... done
     en_ZW.UTF-8... done
     fr_CH.UTF-8... done
     root.UTF-8... done
   Generation complete.
  $ env LC_TIME=root.UTF-8 thunderbird
   [calBackendLoader] Using Thunderbird's builtin libical backend
   *** UTM:SVC TimerManager:registerTimer called after profile-before-change notification. Ignoring timer registration for id: telemetry_modules_ping
  $ sudo mcedit /usr/share/applications/thunderbird.desktop
  $ grep TIME /usr/share/applications/thunderbird.desktop
   Exec=env LC_TIME=root.UTF-8 thunderbird %u

In TB: Help > Troubleshooting information :

Internationalisation & Localisation : Application Settings:
*  Requested Locales  ["en-US"]
*  Available Locales  ["en-GB"]
*  App Locales  ["en-GB","und"]
*  Regional Preferences  ["root"]
*  Default Locale  "und"
*  Operating System
*  System Locales  ["en-US"]
*  Regional Preferences  ["root"]

{{tag>[to_cleanup thunderbird prefs locale date]}}