[BUG] Cannot use two instances of qbittorrent simulateously

[KamilLenica]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

When I create second instance of qbittorrent with port mappet to something different than default 8080 I can only login, but any action e.g. Open settings fails with error

in browser console i can see that qbittorrent answers with 403 error

:8090/:1 The Cross-Origin-Opener-Policy header has been ignored, because the URL's origin was untrustworthy. It was defined either in the final response or a redirect. Please deliver the response using the HTTPS protocol. You can also use the 'localhost' origin instead. See https://www.w3.org/TR/powerful-features/#potentially-trustworthy-origin and https://html.spec.whatwg.org/#the-cross-origin-opener-policy-header.

client.js?locale=C&v=1aui7h2:760
GET http://192.168.31.100:8090/api/v2/sync/maindata?rid=1 403 (Forbidden)

Another instance that I've started couple days ago, with default ports set, works fine

Expected Behavior

I can login and change settings when running two qBittorrent instances

Steps To Reproduce

spin up qbittorrent container with webUI port set to 8080 and second instance with default ports

Environment

- OS: RaspberryPi OS 64bit
- How docker service was installed: package manager

CPU architecture

arm64

Docker creation

---
services:
  qbittorrent:
    image: lscr.io/linuxserver/qbittorrent:latest
    container_name: qbittorrent-manual
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Europe/Warsaw
      - WEBUI_PORT=8090
      - TORRENTING_PORT=6882
    volumes:
      - ~instance1/config:/config
      - /home/leniek/myBook/TORRENT:/downloads/duo #optional
      - /home/leniek/myBook2/:/downloads/solo
    ports:
      - 8090:8090
      - 6882:6882
      - 6882:6882/udp
    restart: unless-stopped


services:
  qbittorrent:
    image: lscr.io/linuxserver/qbittorrent:latest
    container_name: qbittorrent
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Europe/Warsaw
      - WEBUI_PORT=8080
      - TORRENTING_PORT=6881
    volumes:
      - ~instance2:/config
      - /home/leniek/myBook/TORRENT:/downloads/duo #optional
      - /home/leniek/myBook2/:/downloads/solo
    ports:
      - 8090:8080
      - 6882:6881
      - 6882:6881/udp
    restart: unless-stopped

Container logs

leniek@raspberrypi:~/Containers/qbittorrent-manual $ docker logs qbittorrent-manual
[migrations] started
[migrations] no migrations found
───────────────────────────────────────

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

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

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

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

User UID:    1000
User GID:    1000
───────────────────────────────────────
Linuxserver.io version: 5.1.4-r2-ls439
Build-date: 2026-02-03T17:38:06+00:00
───────────────────────────────────────

[custom-init] No custom files found, skipping...
WebUI will be started shortly after internal preparations. Please wait...

******** Information ********
To control qBittorrent, access the WebUI at: http://localhost:8090
The WebUI administrator username is: admin
The WebUI administrator password was not set. A temporary password is provided for this session: 6hy4THCan
You should set your own password in program preferences.
Connection to localhost (::1) 8090 port [tcp/*] succeeded!
[ls.io-init] done.

[github-actions]

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[Roxedus]

Does the 8090 instance work if you log out of the 8080 one, and log into 8090?

[KamilLenica]

If i stop 8080 instance container, then 8090 instance works