wezterm/wezterm · error · anyhow::Error

no size information available

Error message

no size information available

What it means

Thrown by the terminfo/size probing code in termwiz (caps/probed.rs). probe_size writes the XTWINOPS window-report queries (CSI 14 t / 16 t / 18 t) to the terminal and parses replies with the vt parser. It bails with 'no size information available' when the read loop ends and the parser never decoded a Window::ResizeWindowCells or ReportCellSizePixelsResponse report, leaving rows and cols at 0. The catch-all `done = true` arms at lines 220-230 also end the loop early on any unexpected reply, so a terminal that answers with something other than the expected CSI window reports produces the same error.

Source

Thrown at termwiz/src/caps/probed.rs:236

                                }
                            }
                            _ => {
                                done = true;
                            }
                        },
                        _ => {
                            done = true;
                        }
                    },
                    _ => {
                        done = true;
                    }
                }
            });
        }

        if size.rows == 0 && size.cols == 0 {
            bail!("no size information available");
        }

        Ok(size)
    }
}

View on GitHub (pinned to 3ff7522b96)

Solutions

1. Run inside a modern xterm-compatible terminal (WezTerm, xterm, kitty, Windows Terminal via ConPTY) that answers CSI 14 t / 16 t / 18 t
2. Set TERM to a full-featured entry such as xterm-256color instead of dumb, linux, or an unknown value
3. If you only need cell dimensions, skip the probe and use Terminal::get_size_in_cells / UnixTty::get_size (ioctl TIOCGWINSZ), which do not depend on terminal replies
4. When embedding termwiz, wrap probe_size in a timeout/retry so slow terminals get a chance to answer before you give up
5. If you maintain the terminal emulator, implement XTWINOPS window reports (modes 14, 16, 18)

Example fix

// before
let size = probe_size(&mut read, &mut write, false).await?; // bails: no size information available
// after: fall back to the kernel-reported size when the terminal ignores XTWINOPS
let size = match probe_size(&mut read, &mut write, false).await {
    Ok(size) => size,
    Err(_) => {
        let (cols, rows) = terminal.get_size_in_cells()?; // ioctl(TIOCGWINSZ)
        Size { rows, cols, xpixel: 0, ypixel: 0 }
    }
};

// before probing, make sure we are on a real terminal that can answer
if unsafe { libc::isatty(libc::STDOUT_FILENO) } != 1 {
    return fallback_size(); // no tty => the probe cannot succeed
}

let size = match probe_size(&mut read, &mut write, false).await {
    Ok(size) => size,
    Err(_) => {
        // terminal ignores XTWINOPS; use ioctl(TIOCGWINSZ)
        let (cols, rows) = terminal.get_size_in_cells()?;
        Size { rows, cols, xpixel: 0, ypixel: 0 }
    }
};

When it happens

Trigger: Calling TerminalCapabilities::probe_terminal / probe_size on a terminal that does not implement xterm window reporting: it ignores CSI 14/16/18 t, replies with an unrecognized sequence (which trips `done = true`), or replies after the read loop has already given up. ConPTY sessions that emit xtversion queries but no size report, plain `linux` console, `TERM=dumb`, and pipes instead of ptys all hit this.

Common situations: Running termwiz/wezterm-based TUI apps under CI where there is no real TTY; inside screen/tmux configurations that swallow window-report queries; over serial consoles; with TERM unset or set to a minimal terminfo entry; after a terminal emulator upgrade that changed which XTWINOPS modes it supports.

Related errors

• failed to ioctl(TIOCGWINSZ): {}
• failed to ioctl(TIOCSWINSZ): {:?}
• failed to read sigwinch pipe {}
• poll(2) error: {}
• failed to read input {}

AI-assisted analysis of wezterm/wezterm@3ff7522b96 (2026-08-20). Data as JSON: /api/errors/0ca9309393e6f8a5. Report an issue: GitHub.