golang/go · error

zip: writer closed twice

Error message

zip: writer closed twice

What it means

Error "zip: writer closed twice" thrown in golang/go.

Source

Thrown at src/archive/zip/writer.go:90

func (w *Writer) SetComment(comment string) error {
	if len(comment) > uint16max {
		return errors.New("zip: Writer.Comment too long")
	}
	w.comment = comment
	return nil
}

// Close finishes writing the zip file by writing the central directory.
// It does not close the underlying writer.
func (w *Writer) Close() error {
	if w.last != nil && !w.last.closed {
		if err := w.last.close(); err != nil {
			return err
		}
		w.last = nil
	}
	if w.closed {
		return errors.New("zip: writer closed twice")
	}
	w.closed = true

	// write central directory
	start := w.cw.count
	usedZip64 := false
	for _, h := range w.dir {
		// For the Central Directory, we always have the correct sizes.
		//
		// Implementations disagree on what triggers the inclusion of a Zip64
		// extra field: Info-ZIP only writes it if any size or offset EXCEEDS
		// 4GiB - 1, while libarchive writes it if any size REACHES OR EXCEEDS
		// 4GiB - 1, or if the offset EXCEEDS 4GiB - 1. The spec is ambiguous.
		//
		// We conservatively write Zip64 extra fields if any size or offset
		// REACHES OR EXCEEDS 4GiB - 1, to maximize compatibility with readers.
		// There is no ambiguity in parsing, so there is no downside to it.
		//

View on GitHub (pinned to b6b368adc5)

When it happens

Trigger: Thrown at src/archive/zip/writer.go:90 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/6fcde76b9eeee631. Report an issue: GitHub.