chenhg5/cc-connect · error

tmux: create window %q in session %q: %w

Error message

tmux: create window %q in session %q: %w

What it means

When the tmux session exists but the workspace window does not (and windowName != pane), StartSession calls createTmuxWindow and wraps failures as 'tmux: create window %q in session %q: %w'. It is the session-level wrap around the raw `tmux new-window` exec error (errorIndex 351).

Source

Thrown at agent/tmux/tmux.go:187

	windowName, effectiveSessionID := a.windowForSession(sessionName, pane, workDir, sessionID)
	sessionID = effectiveSessionID
	target := sessionName + ":" + windowName

	sessionExists := tmuxSessionExists(sessionName)
	windowExists := sessionExists && tmuxWindowExists(target)

	if !sessionExists {
		if !autoCreate {
			return nil, fmt.Errorf("tmux: session %q does not exist and auto_create is disabled", sessionName)
		}
		if err := createTmuxSession(sessionName, windowName, workDir, shell); err != nil {
			return nil, fmt.Errorf("tmux: create session %q: %w", sessionName, err)
		}
		slog.Info("tmux: created session", "session", sessionName, "window", windowName, "work_dir", workDir)
	} else if !windowExists && windowName != pane {
		// Session exists but this workspace window does not yet — create it.
		if err := createTmuxWindow(sessionName, windowName, workDir); err != nil {
			return nil, fmt.Errorf("tmux: create window %q in session %q: %w", windowName, sessionName, err)
		}
		slog.Info("tmux: created window", "session", sessionName, "window", windowName, "work_dir", workDir)
	}

	newPane := !sessionExists || (!windowExists && windowName != pane)
	if newPane {
		// Always cd to the workspace directory so the shell (and any init_command)
		// starts in the right place, regardless of tmux's -c flag behaviour.
		if workDir != "" && workDir != "." {
			if err := sendKeys(target, "cd "+shellQuote(workDir)); err != nil {
				slog.Warn("tmux: cd failed", "work_dir", workDir, "err", err)
			}
		}
		if initCmd != "" {
			if err := sendKeys(target, initCmd); err != nil {
				slog.Warn("tmux: init_command failed", "cmd", initCmd, "err", err)
			} else {
				slog.Info("tmux: init_command sent", "cmd", initCmd, "target", target)

View on GitHub (pinned to 4000b2338a)

Solutions

1. Check the inner tmux output for the concrete cause
2. Ensure work_dir for the workspace exists
3. Confirm the session still exists (tmux has-session -t <name>) and retry
4. Create the window manually: tmux new-window -d -t <session>: -n <name> -c <dir>

Example fix

// before
# work_dir deleted -> new-window fails
// tmux: create window "feature-x" in session "cc": exit status 1: can't set working directory

// after
mkdir -p /home/user/feature-x
# retry StartSession

if !exec.Command("tmux","has-session","-t",sessionName).Run() == nil { /* recreate session first */ }
if _, err := os.Stat(workDir); err != nil { return err }

sess, err := agent.StartSession(ctx, opts)
if err != nil && strings.Contains(err.Error(), "create window") {
    time.Sleep(200 * time.Millisecond)
    sess, err = agent.StartSession(ctx, opts) // re-checks existence
}

When it happens

Trigger: StartSession against an existing tmux session with window_per_session style layout, where `tmux new-window -d` fails: bad -c workDir, malformed target, or the session dying between the has-session check and the call.

Common situations: Multiple workspaces sharing one tmux session with an invalid work_dir for a new workspace; session killed by another client in a race; window-name/target syntax issues from unusual characters.

Related errors

• %w: %s
• tmux: session %q does not exist and auto_create is disabled
• tmux: create session %q: %w
• antigravitySession: start: %w
• codex app-server start: %w

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/2379c871fdbd1efc. Report an issue: GitHub.