unknown feedback field(s) {}; only "title" and "description"

Error message

unknown feedback field(s) {}; only "title" and "description" are sent (attach files with --files)

What it means

The `baml feedback` command only transmits "title" and "description" fields to PostHog; any other keys in a --json payload are rejected so nothing is silently dropped. The error lists the offending key names and suggests attaching files with --files instead.

Source

Thrown at baml_language/crates/baml_cli/src/feedback_command.rs:389

            if let Some(value) = flag {
                obj.insert(key.to_string(), Value::String(value.clone()));
            }
        }

        // Whitelist: only the documented fields ship. Anything else in a
        // piped payload (stray script fields, PostHog-special keys like
        // `$set`) is rejected rather than silently transmitted. `files` is
        // deliberately NOT accepted from JSON: a piped payload naming local
        // paths would let untrusted payload content exfiltrate arbitrary
        // files. Attachments come only from the `--files` flag (trusted CLI
        // input).
        let unknown: Vec<&str> = obj
            .keys()
            .map(String::as_str)
            .filter(|k| !matches!(*k, "title" | "description"))
            .collect();
        if !unknown.is_empty() {
            return Err(anyhow::anyhow!(
                "unknown feedback field(s) {}; only \"title\" and \
                 \"description\" are sent (attach files with --files)",
                unknown.join(", ")
            ));
        }

        // Validate types, not just names: a non-string field would ship to
        // PostHog while the preview and the local record (which read via
        // `as_str`) silently dropped it.
        for key in ["title", "description"] {
            if let Some(value) = obj.get(key)
                && !value.is_string()
            {
                return Err(anyhow::anyhow!("feedback field \"{key}\" must be a string"));
            }
        }

        let title = obj.get("title").and_then(Value::as_str).unwrap_or("");

View on GitHub (pinned to bd85ce9dee)

Solutions

Remove non-title/description keys from the --json payload, or rename them into the description text.
Use --files to attach logs/screenshots instead of embedding them as JSON fields.
Check key spelling and case: only lowercase "title" and "description" are accepted.

Example fix

// before
baml feedback --json '{"title":"bug","email":"me@x.com"}'
// after
baml feedback --json '{"title":"bug","description":"see attached"}' --files log.txt

Defensive patterns

Strategy: validation

Validate before calling

# allow only known keys before invoking
jq -e 'keys - ["title","description"] | length == 0' payload.json \
  && baml feedback --json "$(cat payload.json)" \
  || echo "payload has unsupported keys"

Try / catch

try {
  run(`baml feedback --json '${payload}'`);
} catch (e) {
  if (String(e).includes('unknown feedback field')) {
    const clean = (({ title, description }) => ({ title, description }))(JSON.parse(payload));
    run(`baml feedback --json '${JSON.stringify(clean)}'`);
  }
}

Prevention

Restrict feedback JSON payloads to title and description keys
Use --files for attachments instead of extra JSON fields
Use exact lowercase key names

When it happens

Trigger: Running `baml feedback --json '{...}'` where the JSON object contains keys other than title/description (e.g. "email", "logs", "body").

Common situations: Reusing a generic feedback JSON template with extra fields; trying to attach log contents inline as a JSON field instead of using --files; typos like "titel" or "Title" (case mismatch).

Understand the failure class

Background: "Unknown argument", "Invalid value", and "must be one of": invalid CLI argument errors explained — this error's family across 35 libraries.

Related errors

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/e85c0a63a01ce8ce. Report an issue: GitHub.