What causes "Invalid extractor type: %s" in projectdiscovery/nuclei?

Use one of: regex, kval, xpath, json, dsl

Invalid extractor type: %s

Error message

Invalid extractor type: %s

What it means

Raised by toExtractorTypes when a template extractor's type field, after TrimSpace + ToLower, matches none of extractorMappings. Supported extractor types are exactly: regex, kval, xpath, json, dsl (extractor_types.go:30-36). ExtractorTypeHolder.UnmarshalYAML propagates the error, so template compilation fails.

Source

Thrown at pkg/operators/extractors/extractor_types.go:59

}

// GetSupportedExtractorTypes returns list of supported types
func GetSupportedExtractorTypes() []ExtractorType {
	var result []ExtractorType
	for index := ExtractorType(1); index < limit; index++ {
		result = append(result, index)
	}
	return result
}

func toExtractorTypes(valueToMap string) (ExtractorType, error) {
	normalizedValue := normalizeValue(valueToMap)
	for key, currentValue := range extractorMappings {
		if normalizedValue == currentValue {
			return key, nil
		}
	}
	return -1, errors.New("Invalid extractor type: " + valueToMap)
}

func normalizeValue(value string) string {
	return strings.TrimSpace(strings.ToLower(value))
}

func (t ExtractorType) String() string {
	return extractorMappings[t]
}

// ExtractorTypeHolder is used to hold internal type of the extractor
type ExtractorTypeHolder struct {
	ExtractorType ExtractorType `mapping:"true"`
}

func (holder ExtractorTypeHolder) JSONSchema() *jsonschema.Schema {
	gotType := &jsonschema.Schema{
		Type:        "string",

View on GitHub (pinned to 265b3a3dec)

Solutions

Use one of: regex, kval, xpath, json, dsl
For JSON path selection use type: json with a json path expression; for CSS/HTML use type: xpath
Run nuclei -validate to catch it at template load

Example fix

# before
extractors:
  - type: jsonpath
    jsonpath: ['$.user']
# after
extractors:
  - type: json
    json: ['$.user']

Defensive patterns

Strategy: validation

Validate before calling

var validExtractorTypes = map[string]bool{"regex": true, "kval": true, "xpath": true, "json": true, "dsl": true}
func extractorTypeOK(s string) bool { return validExtractorTypes[strings.ToLower(strings.TrimSpace(s))] }

Prevention

Maintain a lint rule whitelisting the five extractor types
Map foreign names (jsonpath->json, css->xpath) in a preprocessing step

When it happens

Trigger: An extractor with type: jsonpath, type: grok, or type: css; any value outside the five-word enum.

Common situations: Names borrowed from other frameworks (jsonpath, css, regex-group); upgrading templates written for forks that added extra extractor kinds.

Related errors

AI-assisted analysis of projectdiscovery/nuclei@265b3a3dec (2026-08-15). Data as JSON: /api/errors/663ac1df7cbaf371. Report an issue: GitHub.