openai/codex · error · SkillParseError

invalid YAML: {0}

Error message

invalid YAML: {0}

What it means

Error "invalid YAML: {0}" thrown in openai/codex.

Source

Thrown at codex-rs/skills/src/parser.rs:35

struct SkillFrontmatterMetadata {
    #[serde(default, rename = "short-description")]
    short_description: Option<String>,
}

/// Validated metadata parsed from a `SKILL.md` frontmatter block.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ParsedSkillFrontmatter {
    pub name: String,
    pub description: String,
    pub short_description: Option<String>,
}

/// Error produced while parsing or validating `SKILL.md` metadata.
#[derive(Debug, Error)]
pub enum SkillParseError {
    #[error("missing YAML frontmatter delimited by ---")]
    MissingFrontmatter,
    #[error("invalid YAML: {0}")]
    InvalidYaml(#[source] serde_yaml::Error),
    #[error("missing field `{0}`")]
    MissingField(&'static str),
    #[error("invalid {field}: {reason}")]
    InvalidField { field: &'static str, reason: String },
}

/// Parses and validates the metadata frontmatter from `SKILL.md` contents.
pub fn parse_skill_frontmatter_metadata(
    contents: &str,
    default_name: impl FnOnce() -> String,
) -> Result<ParsedSkillFrontmatter, SkillParseError> {
    let frontmatter = extract_frontmatter(contents).ok_or(SkillParseError::MissingFrontmatter)?;

    let parsed: SkillFrontmatter = match serde_yaml::from_str(&frontmatter) {
        Ok(parsed) => Ok(parsed),
        Err(original_error) => match repair_frontmatter_scalar_fields(&frontmatter) {
            // Some third-party skills use prose like `description: Build for AWS: ECS`

View on GitHub (pinned to 339751715c)

When it happens

Trigger: Thrown at codex-rs/skills/src/parser.rs:35 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/67b6a590161abeae. Report an issue: GitHub.