chenhg5/cc-connect · error

acp: write %s: %w

Error message

acp: write %s: %w

What it means

Raised by transport.call when serializing/writing a JSON-RPC request for the named method to the agent's stdin fails. It fires when the process stdin pipe is broken (agent exited) or the write is rejected; the pending entry is cleaned up and the whole call aborts.

Source

Thrown at agent/acp/rpc.go:189

func (t *transport) call(ctx context.Context, method string, params any) (json.RawMessage, error) {
	id := t.nextID.Add(1)
	key := fmt.Sprintf("%d", id)
	ch := make(chan rpcOutcome, 1)
	t.pendingMu.Lock()
	t.pending[key] = ch
	t.pendingMu.Unlock()

	req := map[string]any{
		"jsonrpc": "2.0",
		"id":      id,
		"method":  method,
		"params":  params,
	}
	if err := t.writeJSON(req); err != nil {
		t.pendingMu.Lock()
		delete(t.pending, key)
		t.pendingMu.Unlock()
		return nil, fmt.Errorf("acp: write %s: %w", method, err)
	}
	select {
	case <-ctx.Done():
		t.pendingMu.Lock()
		delete(t.pending, key)
		t.pendingMu.Unlock()
		return nil, ctx.Err()
	case out := <-ch:
		if out.err != nil {
			return nil, out.err
		}
		return out.result, nil
	}
}

func (t *transport) sendNotification(method string, params any) error {
	return t.writeJSON(map[string]any{
		"jsonrpc": "2.0",

View on GitHub (pinned to 4000b2338a)

Solutions

1. Check whether the agent process is still alive before sending (session closed errors usually accompany this)
2. Restart the session — a broken stdin pipe is not recoverable on the same transport
3. Look for earlier errors explaining why the agent exited

When it happens

Trigger: Thrown at agent/acp/rpc.go:189 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/ac0e1be61e48c385. Report an issue: GitHub.