zed-industries/zed · error

`{}` must be a positive normal number or `randr`. Got `{}`

Error message

`{}` must be a positive normal number or `randr`. Got `{}`

What it means

When the GPUI_X11_SCALE_FACTOR environment variable parses as an f32, the value must pass valid_scale_factor — a positive, finite, normal number. Numeric-but-invalid values such as 0, negatives, NaN, or infinity fall through to this panic naming the variable and the bad value. Valid alternatives are any positive scale (e.g. 1.5) or the literal `randr` for automatic detection.

Source

Thrown at crates/gpui_linux/src/linux/x11/client.rs:2572

}

enum DpiMode {
    Randr,
    Scale(f32),
    NotSet,
}

fn get_scale_factor(
    connection: &XCBConnection,
    resource_database: &Database,
    screen_index: usize,
) -> f32 {
    let env_dpi = std::env::var(GPUI_X11_SCALE_FACTOR_ENV)
        .ok()
        .map(|var| {
            if var.to_lowercase() == "randr" {
                DpiMode::Randr
            } else if let Ok(scale) = var.parse::<f32>() {
                if valid_scale_factor(scale) {
                    DpiMode::Scale(scale)
                } else {
                    panic!(
                        "`{}` must be a positive normal number or `randr`. Got `{}`",
                        GPUI_X11_SCALE_FACTOR_ENV, var
                    );
                }
            } else if var.is_empty() {
                DpiMode::NotSet
            } else {
                panic!(
                    "`{}` must be a positive number or `randr`. Got `{}`",
                    GPUI_X11_SCALE_FACTOR_ENV, var
                );
            }
        })
        .unwrap_or(DpiMode::NotSet);

View on GitHub (pinned to 9d272b0363)

Solutions

1. Set the variable to a positive scale factor, e.g. GPUI_X11_SCALE_FACTOR=1.5
2. Or set it to `randr` to derive the scale from the monitor
3. Or unset it / set it empty to use the default detection

Example fix

# before
export GPUI_X11_SCALE_FACTOR=0     # panic

# after
export GPUI_X11_SCALE_FACTOR=1.5    # or: randr

# shell: validate before launch
v="${GPUI_X11_SCALE_FACTOR:-}"
[ -z "$v" ] || [ "$v" = randr ] || awk -v x="$v" 'BEGIN{exit !(x>0 && x==x)}' \
  || { echo "bad GPUI_X11_SCALE_FACTOR: $v"; exit 1; }

fn valid_scale_env(v: &str) -> bool {
    v.is_empty()
        || v.eq_ignore_ascii_case("randr")
        || v.parse::<f32>().map(|s| s.is_normal() && s > 0.0).unwrap_or(false)
}

When it happens

Trigger: Launching Zed with GPUI_X11_SCALE_FACTOR set to '0', '-2', 'inf', 'nan', or any non-positive numeric string.

Common situations: Scripts or dotfiles setting the variable from a computed value that produced 0 or a negative number; copy-pasted configs with a placeholder value.

Understand the failure class

Background: "is not a valid" / "Invalid ... value" environment variable errors: how libraries validate env vars and what to do when they reject yours — this error's family across 48 libraries.

Related errors

• `{}` must be a positive number or `randr`. Got `{}`
• X11 connection: File descriptor passing failed
• X11 connection: Insufficient memory
• blocking sender returned without value
• wl_seat below required version: {} < {}

AI-assisted analysis of zed-industries/zed@9d272b0363 (2026-08-20). Data as JSON: /api/errors/031a621d47efccba. Report an issue: GitHub.