[BUG] Warning on login screen after update beyond 15.7.0-ls322

[veletron2]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

After upgrade beyond 15.7.0-ls322 errors seen on identification.php both pre-login and post-login. This occurs on two separate systems. Everything works until a login is attempted.

The error on identification.php is:

Warning: filemtime(): stat failed for ./themes/standard_pages/theme.css in /app/www/public/include/template.class.php on line 1925

Warning: file_get_contents(./themes/standard_pages/theme.css): Failed to open stream: No such file or directory in /app/www/public/include/template.class.php on line 2021

I rolled back, ensured all plugins up-to-date and then tried again with same issue

After attempting to login on one of my systems, I get an empty browser window apart from the error:

Uncaught --> Smarty: Plugin tag 'cssGradient' already registered <-- thrown in /app/www/public/include/smarty/src/Smarty.php on line 751

I am assuming that this is due to the existence of a plugin on this system? Deleting the cookies is the only way to get back to the 'logged out' state from this screen.

Update: Rolled back, updated plugins, rolled forward to latest again and this secondary error post-login is no longer present.

I have 'resolved' the warnings at login by rolling back both installs to 15.7.0-ls322

I am using docker-compose

Expected Behavior

Login completes without errors/warnings

Steps To Reproduce

1. Upgrade from 15.7.0-ls322 to 16.1.0-ls322
2. Site works, however
3. Attempt to login
4. --> Warnings seen on login screen
5. Enter valid username/password
6. --> White screen with error text: 'Uncaught --> Smarty: Plugin tag 'cssGradient' already registered'

Environment

- OS: Asustor NAS (ADM)
- How docker service was installed: package manager

CPU architecture

x86-64

Docker creation

services:
  db:
    container_name: piwigo-omc-db
    image: mariadb:latest
    command: '--default-authentication-plugin=mysql_native_password'
    volumes:
      - db:/var/lib/mysql
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=**************************
      - MYSQL_DATABASE=*******************
      - MYSQL_USER=*****************
      - MYSQL_PASSWORD=*******************
    expose: 
      - 3306
  
  piwigo:
    container_name: piwigo-omc-web
    depends_on:
      - db
    image: ghcr.io/linuxserver/piwigo:latest
    environment:
      - TZ=Europe/London
    volumes:
      - config:/config
      - gallery:/gallery
    ports:
      - 20094:80
    restart: unless-stopped

volumes:
  db:
  config:
  gallery:

Container logs

[migrations] started
[migrations] 01-nginx-site-confs-default: skipped
[migrations] done
usermod: no changes
───────────────────────────────────────

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

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

To support LSIO projects visit:
https://www.linuxserver.io/donate/

───────────────────────────────────────
GID/UID
───────────────────────────────────────

User UID:    911
User GID:    911
───────────────────────────────────────
Linuxserver.io version: 16.1.0-ls322
Build-date: 2025-12-02T16:58:12+00:00
───────────────────────────────────────
    
using keys found in /config/keys
[custom-init] No custom files found, skipping...
[04-Dec-2025 10:50:06] NOTICE: PHP message: PHP Warning:  PHP Startup: Invalid date.timezone value 'UK', using 'UTC' instead in Unknown on line 0
[ls.io-init] done.

[github-actions]

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[joelkrueger]

After upgrading from 15.7.0 to 16.1.0 I am also seeing the "Warning: filemtime(): stat failed for ./themes/standard_pages/theme.css in /app/www/public/include/template.class.php on line 1925" on the login screen. I am not seeing the reported second "Warning: file_get_contents". I have not bothered to attempt to roll back, Aside from this warning on the login screen everything else seems to be working fine and I content to wait for a fix.

[thokich]

I have the same BUG.
docker exec -it piwigo ls -l /app/www/public/themes/
default
elegant
modus
smartpocket
no standard_pages.