[BUG] <title>TypeError: dokuwiki\Parsing\ModeRegistry::__construct()

[RoMi-RP]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

After update the Docker image I got the following error
TypeError: dokuwiki\Parsing\ModeRegistry::__construct(): Argument #1 ($syntax) must be of type string, null given, called in /app/www/public/inc/parserutils.php on line 239

I'm not possible to access my DokuWiki

Expected Behavior

No response

Steps To Reproduce

Start the image in an docker container on a Synology NAS

Environment

- OS:
- How docker service was installed:

CPU architecture

arm64

Docker creation

version: "3.7"

services: 
  dokuwiki:
    build: .
    container_name: dokuwiki
    environment: 
     # - PUID=1000
     # - PGID=1000
      - TZ=Europe/Berlin
    stdin_open: true
    tty: true

    volumes: 
      - /volume1/docker/dokuwiki/data:/usr/share/dokuwiki/data
      - /volume1/docker/dokuwiki/conf:/usr/share/dokuwiki/conf
      - /volume1/docker/dokuwiki/lib:/usr/share/dokuwiki/lib
      - /volume1/docker/dokuwiki/vendor:/usr/share/dokuwiki/vendor
      - /volume1/docker/dokuwiki/plugins:/usr/share/dokuwiki/lib/plugins

    ports: 
      - 8080:80
      - 8443:443 

    restart: unless-stopped

Container logs

2026/08/09 10:06:02 [error] 415#415: *9 FastCGI sent in stderr: "PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "samesitecookie" in /app/www/public/inc/auth.php on line 1426; PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "syntax" in /app/www/public/inc/parserutils.php on line 239" while reading response header from upstream, client: 172.17.0.1, server: _, request: "GET /dokuwiki HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "sfrcloudadv:8080"
2026/08/09 10:07:47 [error] 414#414: *13 FastCGI sent in stderr: "PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "syntax" in /app/www/public/inc/parserutils.php on line 239" while reading response header from upstream, client: 172.17.0.1, server: _, request: "GET /dokuwiki HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "sfrcloudadv:8080"
2026/08/09 10:08:05 [error] 414#414: *13 FastCGI sent in stderr: "PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "samesitecookie" in /app/www/public/inc/auth.php on line 545; PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "syntax" in /app/www/public/inc/parserutils.php on line 239" while reading response header from upstream, client: 172.17.0.1, server: _, request: "GET /dokuwiki HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "sfrcloudadv:8080"
2026/08/09 10:09:14 [error] 415#415: *18 FastCGI sent in stderr: "PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "samesitecookie" in /app/www/public/inc/auth.php on line 545; PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "syntax" in /app/www/public/inc/parserutils.php on line 239" while reading response header from upstream, client: 172.17.0.1, server: _, request: "GET /dokuwiki HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "sfrcloudadv:8080"
2026/08/09 10:09:15 [error] 415#415: *18 FastCGI sent in stderr: "PHP message: PHP Warning:  Undefined array key "hidewarnings" in /app/www/public/inc/ErrorHandler.php on line 169; PHP message: PHP Warning:  Undefined array key "samesitecookie" in /app/www/public/inc/auth.php on line 545" while reading response header from upstream, client: 172.17.0.1, server: _, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "sfrcloudadv:8080", referrer: "http://sfrcloudadv:8080/dokuwiki"

[github-actions]

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[Crash1602]

I’m getting exactly the same error with this version of DokuWiki 2026-07-14a-ls317. Rolling back to 2025-05-14b-ls306 - DokuWiki works fine.

[Crash1602]

I found more Informations here:
https://github.com/linuxserver/docker-dokuwiki/issues/90
https://github.com/dokuwiki/dokuwiki/issues/4692

The DokuWiki Linuxserver.io Image does not updating the PHP-File, so you must paste follow line manually into your Config (e.g. Line 13) and restart DokuWiki - after that LSIO DokuWiki runs without Problems.

dokuwiki/conf/local.php

$conf['syntax'] = 'dw';

[RoMi-RP]

The hint helps to get DokuWiki to work.