BoundaryML/baml · error

feedback payload must be a JSON object like {"title": "..."}

Error message

feedback payload must be a JSON object like {"title": "..."}

What it means

The `baml feedback` CLI command accepts a `--payload` JSON string that is parsed by `parse_payload_json`. This error is thrown when the payload parses as valid JSON but is not a JSON object (e.g. a string, number, array, or boolean). The feedback pipeline requires key/value metadata like {"title": "..."} to attach to the report.

Source

Thrown at baml_language/crates/baml_cli/src/feedback_command.rs:506

    use base64::Engine as _;
    json!(
        files
            .iter()
            .map(|f| json!({
                "name": f.name,
                "mime": f.mime,
                "size_bytes": f.size_bytes,
                "content_base64": base64::engine::general_purpose::STANDARD
                    .encode(f.content.as_deref().unwrap_or_default()),
            }))
            .collect::<Vec<_>>()
    )
}

fn parse_payload_json(raw: &str) -> Result<Value> {
    let value: Value = serde_json::from_str(raw).context("feedback payload is not valid JSON")?;
    if !value.is_object() {
        return Err(anyhow::anyhow!(
            "feedback payload must be a JSON object like {{\"title\": \"...\"}}"
        ));
    }
    Ok(value)
}

// ---------------------------------------------------------------------------
// Local report store: <BAML_HOME>/feedback.json
// ---------------------------------------------------------------------------

#[derive(Debug, Deserialize, Serialize)]
struct FeedbackStore {
    /// Whether `baml feedback` sends anything from this machine.
    #[serde(default = "default_true")]
    enabled: bool,
    /// Reports from this machine, oldest first.
    #[serde(default)]
    reports: Vec<FeedbackRecord>,

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Pass the payload as a JSON object: --payload '{"title": "My feedback"}'
2. Wrap the value in braces if you passed an array or bare string.
3. Validate the JSON locally first: `echo '<payload>' | jq -e 'type == "object"'`.
4. Use single quotes around the payload on Unix shells so braces and quotes survive.

Example fix

// before
baml feedback --payload '"My title"'
// after
baml feedback --payload '{"title": "My title"}'

const payload = JSON.parse(raw);
if (typeof payload !== 'object' || payload === null || Array.isArray(payload)) {
  throw new Error('feedback payload must be a JSON object like {"title": "..."}');
}

function isJsonObject(v: unknown): v is Record<string, unknown> {
  return typeof v === 'object' && v !== null && !Array.isArray(v);
}

When it happens

Trigger: Running `baml feedback --payload 'some string'`, `--payload '[1,2,3]'`, `--payload '42'`, or any non-object JSON literal. Also triggered by quoting mistakes in the shell that strip the braces.

Common situations: Shell quoting mishaps (e.g. double-quoted braces eaten by the shell), pasting a JSON array of fields instead of an object, or passing a bare string title without wrapping it in an object.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• unknown feedback field(s) {}; only "title" and "description"
• feedback field "{key}" must be a string
• feedback needs a title; pass --title "..." or a JSON payload
• invalid Go SDK import path `{import_path}`
• project name cannot be empty

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/eeb0ba3d18f5a4db. Report an issue: GitHub.