[BUG] Documentation: TZ environment variable in docker compose seems to not work, APP_DISPLAY_TIMEZONE does

[Mesman-S]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

When setting up a Bookstack docker image in docker compose i tried to change the timezone settings. In https://hub.docker.com/r/linuxserver/bookstack/ the variable TZ is shown. However this

bookstack:
        image: lscr.io/linuxserver/bookstack:latest
        environment:
            TZ: Europe/Amsterdam

seems to have no effect, but using APP_DISPLAY_TIMEZONE does:

bookstack:
        image: lscr.io/linuxserver/bookstack:latest
        environment:
            APP_DISPLAY_TIMEZONE: Europe/Amsterdam

However the docker hub documentation only mentions TZ, does not mention APP_TIMEZONE and APP_DISPLAY_TIMEZONE that are mentioned here: https://www.bookstackapp.com/docs/admin/language-config/

Expected Behavior

Assuming my use of TZ: Europe/Amsterdam was correct but the ENV variable doesn't do anything:
remove mentions of TZ, and replace with mention of APP_DISPLAY_TIMEZONE

Steps To Reproduce

1. docker compose on linux, using bookstack latest image
2. attempt to change the display timezone with TZ
3. open bookstack and hover a timestamp, check to see which timezone is chosen for display
4. change ENV variable to APP_DISPLAY_TIMEZONE
5. open bookstack again, hover a timestamp and see that now it did take effect

Environment

- OS: CachyOS
- How docker service was installed: distro packagemanager

CPU architecture

x86-64

Docker creation

bookstack:
        image: lscr.io/linuxserver/bookstack:latest
        environment:
            APP_DISPLAY_TIMEZONE: Europe/Amsterdam

Container logs

migrations] started
[migrations] 01-nginx-site-confs-default: skipped
[migrations] 02-default-location: skipped
[migrations] done
───────────────────────────────────────

      ██╗     ███████╗██╗ ██████╗
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      ██║     ███████╗██║██║   ██║
      ██║     ╚════██║██║██║   ██║
      ███████╗███████║██║╚██████╔╝
      ╚══════╝╚══════╝╚═╝ ╚═════╝

   Brought to you by linuxserver.io
───────────────────────────────────────

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GID/UID
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User UID:    33
User GID:    33
───────────────────────────────────────
Linuxserver.io version: v26.03.3-ls256
Build-date: 2026-04-13T19:21:12+00:00
───────────────────────────────────────
    
using keys found in /config/keys
Waiting for DB to be available

   INFO  Nothing to migrate.  

[custom-init] No custom files found, skipping...
[ls.io-init] done.

[github-actions]

Thanks for opening your first issue here! Be sure to follow the relevant issue templates, or risk having this issue marked as invalid.

[aptalca]

Php has its own timezone setting which is only set during first run. If you want to change it later, you can edit the file php-local.ini in the config folder.

[LinuxServer-CI]

This issue has been automatically marked as stale because it has not had recent activity. This might be due to missing feedback from OP. It will be closed if no further activity occurs. Thank you for your contributions.