zed-industries/zed · error · anyhow::Error

Failed to launch kernel: {body}

Error message

Failed to launch kernel: {body}

What it means

Raised in launch_remote_kernel when the HTTP POST to the remote server's /kernels endpoint returns a non-success status. The response body (the server's error message) is interpolated into the message, telling the user why the remote kernel process could not be launched.

Source

Thrown at crates/repl/src/kernels/remote_kernels.rs:55

        // Note: since the path we have locally may not be the same as the one on the remote server,
        // we don't send it. We'll have to evaluate this decision along the way.
        path: None,
    };

    let kernel_launch_request = serde_json::to_string(&kernel_launch_request)?;

    let request = Request::builder()
        .method("POST")
        .uri(&remote_server.api_url("/kernels"))
        .header("Authorization", format!("token {}", remote_server.token))
        .body(AsyncBody::from(kernel_launch_request))?;

    let response = http_client.send(request).await?;

    if !response.status().is_success() {
        let mut body = String::new();
        response.into_body().read_to_string(&mut body).await?;
        anyhow::bail!("Failed to launch kernel: {body}");
    }

    let mut body = String::new();
    response.into_body().read_to_string(&mut body).await?;

    let response: jupyter_websocket_client::Kernel = serde_json::from_str(&body)?;

    Ok(response.id)
}

pub async fn list_remote_kernelspecs(
    remote_server: RemoteServer,
    http_client: Arc<dyn HttpClient>,
) -> Result<Vec<RemoteKernelSpecification>> {
    let url = remote_server.api_url("/kernelspecs");

    let request = Request::builder()
        .method("GET")

View on GitHub (pinned to f4178619ac)

Solutions

1. Verify the remote Jupyter server is running and the API URL/token are correct
2. Check that the requested kernel name exists on the remote server (`jupyter kernelspec list`)
3. Inspect the returned body included in the error for the server-side cause
4. Retry if the server was temporarily unavailable

When it happens

Trigger: Thrown at crates/repl/src/kernels/remote_kernels.rs:55 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/b793dd2120c03ed2. Report an issue: GitHub.