golang/go · error

archive/zip: invalid duplicate FileHeader

Error message

archive/zip: invalid duplicate FileHeader

What it means

Error "archive/zip: invalid duplicate FileHeader" thrown in golang/go.

Source

Thrown at src/archive/zip/writer.go:280

				return false, false
			}
			require = true
		}
	}
	return true, require
}

// prepare performs the bookkeeping operations required at the start of
// CreateHeader and CreateRaw.
func (w *Writer) prepare(fh *FileHeader) error {
	if w.last != nil && !w.last.closed {
		if err := w.last.close(); err != nil {
			return err
		}
	}
	if len(w.dir) > 0 && w.dir[len(w.dir)-1].FileHeader == fh {
		// See https://golang.org/issue/11144 confusion.
		return errors.New("archive/zip: invalid duplicate FileHeader")
	}
	return nil
}

// CreateHeader adds a file to the zip archive using the provided [FileHeader]
// for the file metadata. [Writer] takes ownership of fh and may mutate
// its fields. The caller must not modify fh after calling [Writer.CreateHeader].
//
// This returns a [Writer] to which the file contents should be written.
// The file's contents must be written to the io.Writer before the next
// call to [Writer.Create], [Writer.CreateHeader], [Writer.CreateRaw], or [Writer.Close].
func (w *Writer) CreateHeader(fh *FileHeader) (io.Writer, error) {
	if err := w.prepare(fh); err != nil {
		return nil, err
	}

	// The ZIP format has a sad state of affairs regarding character encoding.
	// Officially, the name and comment fields are supposed to be encoded

View on GitHub (pinned to b6b368adc5)

When it happens

Trigger: Thrown at src/archive/zip/writer.go:280 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/19741716a963fbaa. Report an issue: GitHub.