I don't know anything about open-webui, but normally this sort of error means you're getting a http error, and it's trying to parse the HTML error output from the server as json.
Is there a way for you to take a look at the actual response?
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 - {}
Is this what you are referring to?
Maybe -- if the {} is the response body, then that's definitely valid json. Can you open http://localhost:3000/_app/version.json in a browser to check?
I'm not quite sure what this json file represent, could you please explainwhat caused the issue? Thanks a lot in advance.