github/github-mcp-server · info

failed to write CSV row: %w

Error message

failed to write CSV row: %w

What it means

csv.Writer.Write failed while emitting a data row into the in-memory bytes.Buffer. Because bytes.Buffer writes cannot error and csv field values are plain strings, this is defensive code with no realistic trigger; a failure would indicate resource exhaustion or a modified build rather than problematic row data.

Source

Thrown at pkg/github/csv_output.go:144

	}

	headers := csvHeaders(doc.rows)
	if len(headers) == 0 {
		return buf.String(), nil
	}

	writer := csv.NewWriter(&buf)
	if err := writer.Write(headers); err != nil {
		return "", fmt.Errorf("failed to write CSV header: %w", err)
	}

	for _, row := range doc.rows {
		record := make([]string, len(headers))
		for i, header := range headers {
			record[i] = row[header]
		}
		if err := writer.Write(record); err != nil {
			return "", fmt.Errorf("failed to write CSV row: %w", err)
		}
	}

	writer.Flush()
	if err := writer.Error(); err != nil {
		return "", fmt.Errorf("failed to flush CSV: %w", err)
	}
	return buf.String(), nil
}

func csvDocument(value any) csvOutputDocument {
	switch v := value.(type) {
	case []any:
		return csvOutputDocument{rows: csvRowsFromArray(v)}
	case map[string]any:
		if rows, metadata, ok := primaryRowsFromMap(v); ok {
			return csvOutputDocument{
				metadata: newFlattenedCSVRow(metadata),

View on GitHub (pinned to 0ea1f775a7)

Solutions

1. Reduce result size via pagination or field filters before requesting CSV output
2. Increase memory limits if large CSV exports are expected
3. Report as an invariant violation if it recurs on modest payloads

if err := writer.Write(record); err != nil {
	// in-memory buffer: invariant failure — abort conversion and report payload size
	return "", fmt.Errorf("failed to write CSV row: %w", err)
}

When it happens

Trigger: CSV conversion of a JSON rows array where the buffer write fails — only plausible under extreme memory pressure or in altered code that swaps the buffer for a fallible writer.

Common situations: Huge paginated outputs converted to CSV in constrained containers; effectively unreachable otherwise.

Related errors

• failed to write CSV header: %w
• failed to flush CSV: %w
• failed to unmarshal JSON text: %w
• failed to marshal discussions: %w
• failed to marshal discussion: %w

AI-assisted analysis of github/github-mcp-server@0ea1f775a7 (2026-08-15). Data as JSON: /api/errors/da04db14b3e5f12a. Report an issue: GitHub.