vectordotdev/vector · error

Transform is missing

Error message

Transform {transform_key} is missing

What it means

After finding the `transforms` mapping, `wrap_transform` looks up the single component key inside it. If the `transforms` mapping is empty or contains no value under the extracted key (e.g. it holds a scalar or null), it reports that the named transform is missing.

Solutions

1. Ensure the `transforms` mapping contains an entry whose key is the transform's identifier with a full config mapping as its value.
2. Remove empty placeholder `transforms:` sections from example files.
3. Confirm the transform key in the YAML matches the component name used elsewhere (e.g. for `inputs` wiring).

Example fix

// before
transforms: {}

// after
transforms:
  my_transform:
    type: remap
    source: ". = ."

const t = root.transforms;
const keys = Object.keys(t ?? {});
if (keys.length !== 1 || t[keys[0]] === null || typeof t[keys[0]] !== 'object') {
  throw new Error('transforms must contain exactly one component key with a full config mapping');
}

function hasTransformEntry(transforms) {
  const entries = Object.entries(transforms ?? {}).filter(([, v]) => v !== null && typeof v === 'object');
  return entries.length >= 1;
}

When it happens

Trigger: The `transforms:` section exists but is empty, or `transforms.<transform_key>` is null/a non-mapping that `mapping_value` cannot resolve to the declared key.

Common situations: A placeholder `transforms:` with no entries was committed; the key inside `transforms` was renamed but the check still expects the mapping-key match; YAML typo producing a null value under the key.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• has no component identifier
• Sink example has no sinks section
• Sink is missing
• Source example has no sources section
• Source output has no name

AI-assisted analysis of vectordotdev/vector@bdb87aeaa4 (2026-09-16). Data as JSON: /api/errors/ee9aef538c32cd7e. Report an issue: GitHub.

Appendix: source

Thrown at vdev/src/commands/check/component_examples.rs:219

        YamlValue::Mapping(sinks),
    );
    Ok(YamlValue::Mapping(root))
}

fn wrap_transform(component_yaml: &YamlValue, component: &Value) -> Result<Option<YamlValue>> {
    let Some(source) = validation_source(component) else {
        return Ok(None);
    };
    let root = yaml_mapping(component_yaml, "transform example")?;
    let transforms = yaml_mapping(
        mapping_value(&root, "transforms")
            .ok_or_else(|| anyhow!("Transform example has no transforms section"))?,
        "transform example transforms",
    )?;
    let transform_key = mapping_key(&transforms, "transform example")?;
    let mut transform = yaml_mapping(
        mapping_value(&transforms, &transform_key)
            .ok_or_else(|| anyhow!("Transform {transform_key} is missing"))?,
        "transform configuration",
    )?;
    transform.insert(
        YamlValue::String("inputs".to_owned()),
        yaml_list(["_validate_source"]),
    );

    let named_outputs = route_outputs(&transform);
    let mut sinks = Mapping::new();
    if named_outputs.is_empty() {
        sinks.insert(
            YamlValue::String("_validate_sink".to_owned()),
            blackhole(&transform_key),
        );
    } else {
        for output in named_outputs {
            sinks.insert(
                YamlValue::String(format!("_validate_sink_{output}")),

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