sigoden/aichat · error

Invalid response event-stream. content-type

Error message

Invalid response event-stream. content-type: {content_type}, data: {text}

What it means

The streaming endpoint responded with a Content-Type that is not text/event-stream (e.g. application/json from a non-streaming API, or text/html from an error page). This means the request reached an HTTP server but not a valid SSE endpoint — typically a wrong base URL, a model/endpoint that does not support streaming, or a proxy stripping the event-stream content type. The response body is dumped to aid diagnosis.

Solutions

1. Verify the base URL and path target a streaming-capable SSE endpoint
2. Check that the model supports streaming and that the request was formed with stream: true
3. If behind a proxy, ensure it preserves the text/event-stream Content-Type and does not buffer the response
4. Compare the dumped body with provider docs to identify whether an error JSON was returned instead of a stream

When it happens

Trigger: Thrown at src/client/stream.rs:128 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of sigoden/aichat@82976d349a (2026-09-09). Data as JSON: /api/errors/33fc55432a0d7034. Report an issue: GitHub.

Appendix: source

Thrown at src/client/stream.rs:128

            Err(err) => {
                match err {
                    EventSourceError::StreamEnded => {}
                    EventSourceError::InvalidStatusCode(status, res) => {
                        let text = res.text().await?;
                        let data: Value = match text.parse() {
                            Ok(data) => data,
                            Err(_) => {
                                bail!(
                                    "Invalid response data: {text} (status: {})",
                                    status.as_u16()
                                );
                            }
                        };
                        catch_error(&data, status.as_u16())?;
                    }
                    EventSourceError::InvalidContentType(header_value, res) => {
                        let text = res.text().await?;
                        bail!(
                            "Invalid response event-stream. content-type: {}, data: {text}",
                            header_value.to_str().unwrap_or_default()
                        );
                    }
                    _ => {
                        bail!("{}", err);
                    }
                }
                es.close();
            }
        }
    }
    Ok(())
}

pub async fn json_stream<S, F, E>(mut stream: S, mut handle: F) -> Result<()>
where
    S: Stream<Item = Result<bytes::Bytes, E>> + Unpin,

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