chenhg5/cc-connect · error

ping timeout

Error message

ping timeout

What it means

Handshake step 1 waits up to 10 seconds for the `ping` response. If the timer fires first (no reply, no context cancellation), handshake returns the literal error "ping timeout". It means the copilot process is alive or hung but its JSON-RPC loop is not answering.

Source

Thrown at agent/copilot/session.go:169

	if err := cs.handshake(resumeSessionID); err != nil {
		_ = cs.Close()
		return nil, fmt.Errorf("copilotSession: handshake failed: %w", err)
	}

	return cs, nil
}

func (cs *copilotSession) handshake(resumeSessionID string) error {
	// Step 1: Ping
	_, pingCh := cs.rpc.call("ping", nil)
	select {
	case resp := <-pingCh:
		if resp.Error != nil {
			return fmt.Errorf("ping: %w", resp.Error)
		}
		slog.Debug("copilotSession: ping OK")
	case <-time.After(10 * time.Second):
		return fmt.Errorf("ping timeout")
	case <-cs.ctx.Done():
		return cs.ctx.Err()
	}

	// Step 2: Create or resume session
	if resumeSessionID != "" && resumeSessionID != core.ContinueSession {
		_, resumeCh := cs.rpc.call("session.resume", cs.sessionConfig(resumeSessionID))
		select {
		case resp := <-resumeCh:
			if resp.Error != nil {
				slog.Warn("copilotSession: resume failed, creating new session", "error", resp.Error)
				return cs.createSession()
			}
			cs.sessionID.Store(resumeSessionID)
			slog.Info("copilotSession: session resumed", "sessionId", resumeSessionID)
		case <-time.After(10 * time.Second):
			return fmt.Errorf("session.resume timeout")
		case <-cs.ctx.Done():

View on GitHub (pinned to 4000b2338a)

Solutions

1. Check the copilot CLI stderr buffer for interactive prompts (login prompts hang the handshake)
2. Run the CLI manually to confirm it starts non-interactively and answers requests
3. If cold start is slow in your environment, this timeout is the guard — pre-warm the agent or accept the failure and retry
4. Verify stdout is pure LSP-framed JSON-RPC (a framing bug makes every read hang) — see readMessage errors
5. Increase the 10s timeout in session.go only after confirming the child is genuinely slow, not hung

Example fix

// before: CLI launches interactively and hangs
child := exec.Command(binPath)  // prompts "sign in?" on first run
// after: pre-authenticate so startup never blocks on stdin
// run once as the daemon user: copilot auth login
child := exec.Command(binPath, "--headless") // or equivalent non-interactive flag

// ensure the CLI can start and respond non-interactively before session creation
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
out, err := exec.CommandContext(ctx, copilotPath, "--version").Output()
cancel()
if err != nil || len(bytes.TrimSpace(out)) == 0 {
    return fmt.Errorf("copilot CLI unresponsive/interactive: %w", err)
}

sess, err := StartSession(ctx, cfg, resumeID)
if err != nil {
    if strings.Contains(err.Error(), "ping timeout") {
        // one retry; repeated timeouts mean the CLI hangs and needs diagnosis
        if attempt++; attempt < 2 {
            return StartSession(ctx, cfg, "")
        }
        return fmt.Errorf("copilot ping timeout after retry: %w", err)
    }
    return err
}

When it happens

Trigger: handshake() from newCopilotSession: no ping response arrives on pingCh within time.After(10*time.Second) — reader goroutine stuck, child process hung, output not LSP-framed so the reader never completes a message, or the CLI is blocked on auth/network.

Common situations: Copilot CLI waiting for interactive login on stdout/stdin; child stuck due to a full stderr/stdout pipe; a very slow cold start exceeding 10s; output framing mismatch so readLoop can't parse any message; CI machines with heavy startup latency.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

• Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

• copilotSession: handshake failed: %w
• copilot: session.delete: %s
• copilot: session.delete failed: %s
• copilot: session.delete failed: unknown error
• ping: %w

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/3a453cc5ac563dbe. Report an issue: GitHub.