SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

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I started a webui container and then I started to get this error in OpenWebUI interface.

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

latest Ollama on windows
latest Open WebUI in docker desktop

according to a post online, I should set ENABLE_WEBSOCKET_SUPPORT=True in my docker compose, but I'm not using reverse proxy. Is ENABLE_WEBSOCKET_SUPPORT=True necessary?

What could a possible solution be for this?

My docker compose

services:
  open-webui:
    image: ghcr.io/open-webui/open-webui:cuda 
    container_name: open-webui
    restart: unless-stopped
    ports:
      - "3000:8080"
    extra_hosts:
      - "host.docker.internal:host-gateway"
    volumes:
      - ./data:/app/backend/data
    deploy:
      resources:
        reservations:
          devices:
            - driver: nvidia
              count: all
              capabilities: [gpu]
volumes:
  open-webui:

log

2025-06-21 10:43:57 open-webui  | 2025-06-21 00:43:57.601 | INFO     | uvicorn.protocols.http.httptools_impl:send:476 - 172.21.0.1:37276 - "GET /_app/version.json HTTP/1.1" 304 - {}
2025-06-21 10:44:58 open-webui  | 2025-06-21 00:44:58.114 | INFO     | uvicorn.protocols.http.httptools_impl:send:476 - 172.21.0.1:49064 - "GET /_app/version.json HTTP/1.1" 304 - {}
2025-06-21 10:45:58 open-webui  | 2025-06-21 00:45:58.779 | INFO     | uvicorn.protocols.http.httptools_impl:send:476 - 172.21.0.1:55958 - "GET /_app/version.json HTTP/1.1" 304 - {}
2025-06-21 10:46:59 open-webui  | 2025-06-21 00:46:59.179 | INFO     | uvicorn.protocols.http.httptools_impl:send:476 - 172.21.0.1:47424 - "GET /_app/version.json HTTP/1.1" 304 - {}

UPDATE:

when I open http://localhost:3000/ in another browser it works perfectly fine. I think the issue is about the browser I used (firefox with a lot extension installed and setting tweaked)

UPDATE 2:
The problem is with this plugin https://addons.mozilla.org/en-US/firefox/addon/chameleon-ext/ Everything works fine with it disabled.

The reason my chameleon breaks openwebui is because I changed a setting in it that it blocks all websocket connection

Thank you everyone for your help

[email protected]

Even when you're not using a reverse proxy, you're still going to be streaming to that socket.

So I woild recomend that flag still and retest, because the only time I personally have seen that error is when the socket was closed to streaming and it fails to get returned data.

[email protected]

i would start by seeing what the actually API response is. i haven’t used OpenWebUI, but to me this looks like some kind of error response from the server. you could use an API tester like Bruno.
also check your Ollama logs to see if it’s getting the request and any other output there.

[email protected]

Add an environment block at the same level as image: and enable websocket. add

- OLLAMA_API_BASE_URL=http://host.docker.internal:11434/api

to the environment block as well. Also make sure olama is running correctly and and the correct port

I think it's a routing problem. Webui needs access to ollama running directly on Windows, and it's not part of the docker compose network.

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In my experience that is almost always the server returning an html error page.

Start with inspecting that actual response the first character is probably <. The rest of it is likely to be a "not found" or "internal server error" (being the most common) page.

Then look at logs...

[email protected]

Hi how do I check the response?

[email protected]

when I open http://localhost:3000/ in another browser it works perfectly fine. I think the issue is about the browser I used (firefox with a lot extension installed and setting tweaked)

[email protected]

when I open http://localhost:3000/ in another browser it works perfectly fine. I think the issue is about the browser I used (firefox with a lot extension installed and setting tweaked)

[email protected]

thanks I have enabled websocket but the issue still exists

when I open http://localhost:3000/ in another browser it works perfectly fine. I think the issue is about the browser I used (firefox with a lot extension installed and setting tweaked)

[email protected]

fuckin weird that an extension would inject invalid JSON into an API payload. if you’re gonna make a shady plugin at least test it lol

anyway, if that’s truly the issue i’d be worried about what my extensions were doing, personally.

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all the extension I installed is from https://addons.mozilla.org/, is there a quick way to check which extension is "inject invalid JSON into an API payload" ?

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Yeah, trying an incognito window without the extensions would be the best place to start then, if you want to continue to use Firefox for it.

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The problem is with this plugin https://addons.mozilla.org/en-US/firefox/addon/chameleon-ext/ Everything works fine with it disabled. Don't now why though

[email protected]

The problem is with this plugin https://addons.mozilla.org/en-US/firefox/addon/chameleon-ext/ Everything works fine with it disabled.

The reason my chameleon breaks openwebui is because I changed a setting in it that it blocks all websocket connection

[email protected]

The problem is with this plugin https://addons.mozilla.org/en-US/firefox/addon/chameleon-ext/ Everything works fine with it disabled.

The reason my chameleon breaks openwebui is because I changed a setting in it that it blocks all websocket connection

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ah that makes sense

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It could be the accepts header then... check if the request includes accetps: application/json

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F12 should open the browser developer tools, one panel will be the network requests.

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SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data