What causes "expected '(' but found %v at facet" in dgraph-io/dgraph?

Wrap the facet list in parentheses: (key=value, key2=value2).

expected '(' but found %v at facet

Error message

expected '(' but found %v at facet

What it means

Error raised by the RDF parser in chunker/rdf_parser.go while parsing facets when the parser expects an opening '(' for a value but encounters a different token, which is reported via %v. Indicates malformed facet syntax; fix by correcting the facet value format.

Source

Thrown at chunker/rdf_parser.go:266

		return "", errors.New("empty variable name in function call")
	}
	s += "(" + item.Val + ")"

	it.Next()
	if item = it.Item(); item.Typ != itemRightRound {
		return "", fmt.Errorf("expected ')', found: %s", item.Val)
	}

	return s, nil
}

func parseFacetsRDF(it *lex.ItemIterator, rnq *api.NQuad) error {
	if !it.Next() {
		return errors.New("unexpected end of facets")
	}
	item := it.Item()
	if item.Typ != itemLeftRound {
		return fmt.Errorf("expected '(' but found %v at facet", item.Val)
	}

	for it.Next() { // parse one key value pair
		// parse key
		item = it.Item()
		if item.Typ != itemText {
			return fmt.Errorf("expected key but found %v", item.Val)
		}
		facetKey := strings.TrimSpace(item.Val)
		if len(facetKey) == 0 {
			return errors.New("empty facetKeys not allowed")
		}
		// parse =
		if !it.Next() {
			return errors.New("unexpected end of facets")
		}
		item = it.Item()
		if item.Typ != itemEqual {

View on GitHub (pinned to 759e242be6)

Solutions

Wrap the facet list in parentheses: (key=value, key2=value2).
If the trailing token is not a facet, remove it from the line.
Check the facet syntax documented for RDF parsing: object followed by (key=value).

Example fix

// before
"<s> <p> \"v\" score=0.9 ."
// after
"<s> <p> \"v\" (score=0.9) ."

Defensive patterns

Strategy: validation

Validate before calling

func facetSyntaxOK(line string) bool {
	i := strings.Index(line, "\"")
	rest := line[i+1:]
	if j := strings.LastIndex(rest, "\""); j >= 0 {
		after := strings.TrimSpace(rest[j+1:])
		return after == "." || strings.HasPrefix(after, "(")
	}
	return true
}

Try / catch

if _, err := ParseRDF(line); err != nil {
	if strings.Contains(err.Error(), "expected '(' but found") {
		return fmt.Errorf("facets must be wrapped in parentheses: %w", err)
	}
	return err
}

Prevention

Always wrap facet lists in (key=value).
Don't copy query-language facet syntax into RDF lines.
Run a sample line through ParseRDF before large imports.

When it happens

Trigger: ParseRDF input where a token follows the object that was meant as a facet but is not parenthesized, e.g. '<s> <p> "v" score=0.9 .' — the parser sees 'score' where '(' was required.

Common situations: Writing facets without wrapping them in parentheses; copying facet syntax from query language instead of RDF facet syntax; language tags or datatype suffixes misread as facet starts.

Related errors

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/fdaaca13a0379133. Report an issue: GitHub.