golang/go · error

ReadZip: encoded file exceeds allowed size

Error message

ReadZip: encoded file exceeds allowed size

What it means

ReadZip funnels the VCS-produced archive (git/hg archive) through a limitedWriter capped at the caller-supplied maxSize, which ultimately derives from codehost.MaxZipFile (500 MiB). If the encoded zip would exceed the cap, the writer short-writes and returns this error, aborting the read.

Source

Thrown at src/cmd/go/internal/modfetch/codehost/vcs.go:628

	if err != nil {
		return nil, err
	}

	unlock, err := r.mu.Lock()
	if err != nil {
		return nil, err
	}
	defer unlock()

	f, err := os.CreateTemp("", "go-readzip-*.zip")
	if err != nil {
		return nil, err
	}
	if r.cmd.doReadZip != nil {
		lw := &limitedWriter{
			W:               f,
			N:               maxSize,
			ErrLimitReached: errors.New("ReadZip: encoded file exceeds allowed size"),
		}
		err = r.cmd.doReadZip(ctx, lw, r.dir, rev, subdir, r.remote)
		if err == nil {
			_, err = f.Seek(0, io.SeekStart)
		}
	} else if r.cmd.vcs == "fossil" {
		// If you run
		//	fossil zip -R .fossil --name prefix trunk /tmp/x.zip
		// fossil fails with "unable to create directory /tmp" [sic].
		// Change the command to run in /tmp instead,
		// replacing the -R argument with an absolute path.
		args := r.cmd.readZip(rev, subdir, r.remote, filepath.Base(f.Name()))
		for i := range args {
			if args[i] == ".fossil" {
				args[i] = filepath.Join(r.dir, ".fossil")
			}
		}
		_, err = Run(ctx, filepath.Dir(f.Name()), args)

View on GitHub (pinned to b6b368adc5)

Solutions

1. Narrow the module: pick a subdir, split the module, or remove large generated/binary files from the repository.
2. Pin to a smaller revision or tag that predates the bulk that pushed it over the limit.
3. If you control the toolchain, raise codehost.MaxZipFile and rebuild go; otherwise request the upstream maintainer trim the repo.

When it happens

Trigger: A module's zip representation produced by the VCS for the requested revision/subdir exceeds the maxSize limit passed to ReadZip.

Common situations: Very large repositories fetched as a module; requesting a wide revision range or no subdir so the whole repo is archived; vendored large binaries or generated files inside the repo; a heavy subdirectory selected as subdir.

Related errors

• https fetch: %v
• parsing %s: %v
• parse %s: %v
• parse %s: no go-import meta tags (%s)
• %s and %s disagree about go-import for %s

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/0c33e9012264c6d8. Report an issue: GitHub.