github/copilot-sdk · error

writing binary file

Error message

writing binary file: %w

What it means

After successfully creating the destination file, installAt copies the embedded CLI stream into it with io.Copy. If that copy (or the deferred close) fails, the error is wrapped as "writing binary file". The binary on disk may be truncated or empty at this point.

Solutions

1. Check free disk space and quotas on the install volume
2. Verify the source of config.Cli is intact (hash its content before install)
3. Remove the partially written finalPath and retry the install
4. Retry after transient I/O failure; investigate storage health if persistent

Example fix

// before
f, _ := os.OpenFile(finalPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
io.Copy(f, cfg.Cli) // fails: writing binary file: no space left on device
// after
if err := checkFreeSpace(installDir, cfg.CliSize); err != nil { return err } // preflight
if _, err := io.Copy(f, cfg.Cli); err != nil { os.Remove(finalPath); return err }

var avail uint64
if st, err := os.Stat(installDir); err == nil {
    if ok, _ := checkFreeSpace(st, expectedSize); !ok { return errors.New("insufficient disk space") }
}

path, err := embeddedcli.Install(ctx, cfg)
if err != nil && strings.Contains(err.Error(), "writing binary file") {
    os.Remove(path) // clean partial write
    return fmt.Errorf("install failed mid-write (disk full?): %w", err)
}

When it happens

Trigger: io.Copy(f, config.Cli) or f.Close() returns an error: disk-full mid-write, source reader (config.Cli) returns a read error, or close-time flush fails.

Common situations: Disk quota exceeded mid-install; the embedded CLI reader came from a truncated or corrupt embedded asset; network-backed source (e.g. HTTP body) interrupted.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• creating binary file
• writing license file
• ELF probe too small: + size + bytes
• Program header table offset outside probe window: + phoff
• PT_INTERP extends past probe window; increase probe size

AI-assisted analysis of github/copilot-sdk@cd8cf15dc3 (2026-09-09). Data as JSON: /api/errors/3539eb10ce04d47b. Report an issue: GitHub.

Appendix: source

Thrown at go/internal/embeddedcli/embeddedcli.go:299

		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)
		}
	}

	if config.RuntimeExecutable != nil {
		path, err := installRuntimePair(installDir)
		if err != nil {
			return "", err
		}
		runtimePath = path
	}

	// Install the native in-process runtime library (if bundled) next to the CLI.
	// Fail closed on any hash mismatch; never place unverified native code.

View on GitHub (pinned to cd8cf15dc3)