grafana/k6 · error

failed to read the first line; reason: %w

Error message

failed to read the first line; reason: %w

What it means

Error "failed to read the first line; reason: %w" thrown in grafana/k6.

Source

Thrown at internal/js/modules/k6/experimental/csv/reader.go:62

	}

	if options.Delimiter == 0 {
		options.Delimiter = ','
	}

	csvParser := csv.NewReader(r)
	csvParser.Comma = options.Delimiter

	reader := &Reader{
		csv:     csvParser,
		options: options,
	}

	asObjectsEnabled := options.AsObjects.Valid && options.AsObjects.Bool
	if asObjectsEnabled {
		header, err := csvParser.Read()
		if err != nil {
			return nil, fmt.Errorf("failed to read the first line; reason: %w", err)
		}
		reader.columnNames = header
		reader.currentLine.Add(1)
	}

	if options.SkipFirstLine && (!options.FromLine.Valid || options.FromLine.Int64 == 0) {
		if _, err := csvParser.Read(); err != nil {
			return nil, fmt.Errorf("failed to skip the first line; reason: %w", err)
		}

		reader.currentLine.Add(1)
	}

	if options.FromLine.Valid && options.FromLine.Int64 > 0 {
		for reader.currentLine.Load() < options.FromLine.Int64 {
			if _, err := csvParser.Read(); err != nil {
				return nil, fmt.Errorf("failed to skip lines until line %d; reason: %w", options.FromLine.Int64, err)
			}

View on GitHub (pinned to 93accf6570)

When it happens

Trigger: Thrown at internal/js/modules/k6/experimental/csv/reader.go:62 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/59316cbb2b3685c1. Report an issue: GitHub.