golang/go · error

zip: size cannot be negative

Error message

zip: size cannot be negative

What it means

Error "zip: size cannot be negative" thrown in golang/go.

Source

Thrown at src/archive/zip/reader.go:108

		return nil, err
	}
	r.f = f
	return r, err
}

// NewReader returns a new [Reader] reading from r, which is assumed to
// have the given size in bytes.
//
// If any file inside the archive uses a non-local name
// (as defined by [filepath.IsLocal]) or a name containing backslashes
// and the GODEBUG environment variable contains `zipinsecurepath=0`,
// NewReader returns the reader with an [ErrInsecurePath] error.
// A future version of Go may introduce this behavior by default.
// Programs that want to accept non-local names can ignore
// the [ErrInsecurePath] error and use the returned reader.
func NewReader(r io.ReaderAt, size int64) (*Reader, error) {
	if size < 0 {
		return nil, errors.New("zip: size cannot be negative")
	}
	zr := new(Reader)
	var err error
	if err = zr.init(r, size); err != nil && err != ErrInsecurePath {
		return nil, err
	}
	return zr, err
}

func (r *Reader) init(rdr io.ReaderAt, size int64) error {
	end, baseOffset, err := readDirectoryEnd(rdr, size)
	if err != nil {
		return err
	}
	r.r = rdr
	r.baseOffset = baseOffset
	// Since the number of directory records is not validated, it is not
	// safe to preallocate r.File without first checking that the specified

View on GitHub (pinned to b6b368adc5)

When it happens

Trigger: Thrown at src/archive/zip/reader.go:108 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/70fa832be832d309. Report an issue: GitHub.