github/copilot-sdk · error

creating binary file

Error message

creating binary file: %w

What it means

installAt opens the destination file with os.OpenFile(finalPath, O_WRONLY|O_CREATE|O_TRUNC, 0755) to write the embedded CLI binary. If the open itself fails, the error is wrapped as "creating binary file". This typically means the path is unwritable or blocked.

Solutions

1. Check parent directory exists and is writable by the current user (ls -ld, chmod/chown)
2. Ensure finalPath is not a directory and no immutable/squashfs mount blocks writes
3. Free disk space if the volume is full
4. Run the installer with sufficient privileges or choose another installDir

Example fix

// before
installDir := "/usr/local/bin" // permission denied for non-root
// after
installDir := filepath.Join(os.Getenv("HOME"), ".local", "bin")
os.MkdirAll(installDir, 0o755)

dir := filepath.Dir(finalPath)
if fi, err := os.Stat(dir); err != nil || !fi.IsDir() { os.MkdirAll(dir, 0o755) }
if fi, err := os.Stat(finalPath); err == nil && fi.IsDir() { return errors.New("target is a directory") }
if err := unix.Access(dir, unix.W_OK); err != nil { return err }

path, err := embeddedcli.Install(ctx, cfg)
if err != nil {
    var pe *fs.PathError
    if errors.As(err, &pe) && pe.Op == "open" {
        return fmt.Errorf("cannot write %s: check permissions/space: %w", pe.Path, err)
    }
    return err
}

When it happens

Trigger: os.OpenFile on finalPath fails: parent directory does not exist, permission denied, finalPath is a directory, disk full, or the path is on a read-only mount.

Common situations: Install directory created with wrong permissions; running as non-root where root is required; finalPath collides with an existing directory of the same name; container image with read-only filesystem.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

• failed to create output file
• writing binary file
• writing license file
• approveAll cannot be used when managed settings are enabled
• Permission handlers cannot return 'no-result' when…

AI-assisted analysis of github/copilot-sdk@cd8cf15dc3 (2026-09-09). Data as JSON: /api/errors/78c02ef1158789ae. Report an issue: GitHub.

Appendix: source

Thrown at go/internal/embeddedcli/embeddedcli.go:289

			}
			runtimePath = path
		}
		if config.RuntimeLib != nil {
			libPath, err := installRuntimeLib(installDir)
			if err != nil {
				return "", err
			}
			runtimeLibPath = libPath
		}
		if err := installRuntimeAssets(installDir); err != nil {
			return "", err
		}
		return finalPath, nil
	}

	f, err := os.OpenFile(finalPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
	if err != nil {
		return "", fmt.Errorf("creating binary file: %w", err)
	}
	_, err = io.Copy(f, config.Cli)
	if err1 := f.Close(); err1 != nil && err == nil {
		err = err1
	}
	if closer, ok := config.Cli.(io.Closer); ok {
		closer.Close()
	}
	if err != nil {
		return "", fmt.Errorf("writing binary file: %w", err)
	}
	if len(config.License) > 0 {
		licensePath := finalPath + ".license"
		if err := os.WriteFile(licensePath, config.License, 0644); err != nil {
			return "", fmt.Errorf("writing license file: %w", err)
		}
	}

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