zed-industries/zed · error

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

Error message

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

What it means

The other invalid-value branch for GPUI_X11_SCALE_FACTOR: the variable is not the literal `randr`, does not parse as an f32, and is not empty. Any malformed non-numeric string (e.g. 'auto', '1.5x', '1,5' with a comma) hits this panic naming the variable and the offending value.

Source

Thrown at crates/gpui_linux/src/linux/x11/client.rs:2580

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);

    match env_dpi {
        DpiMode::Scale(scale) => {
            log::info!(
                "Using scale factor from {}: {}",
                GPUI_X11_SCALE_FACTOR_ENV,
                scale
            );

View on GitHub (pinned to 9d272b0363)

Solutions

1. Use a plain decimal number with a dot: GPUI_X11_SCALE_FACTOR=1.5
2. Use the exact literal `randr` (lowercase per the comparison, though the check is case-insensitive for 'randr') for automatic scaling
3. Unset the variable or set it empty to fall back to default detection

Example fix

# before
export GPUI_X11_SCALE_FACTOR=1,5x   # panic

# after
export GPUI_X11_SCALE_FACTOR=1.5     # or: randr

# shell: reject non-numeric values early
v="${GPUI_X11_SCALE_FACTOR:-}"
[ -z "$v" ] || [ "${v,,}" = randr ] || [[ "$v" =~ ^[0-9]+([.][0-9]+)?$ ]] \
  || { echo "GPUI_X11_SCALE_FACTOR must be a number or 'randr'"; exit 1; }

fn scale_env_is_wellformed(v: &str) -> bool {
    v.is_empty() || v.eq_ignore_ascii_case("randr") || v.parse::<f32>().is_ok()
}

When it happens

Trigger: Launching with GPUI_X11_SCALE_FACTOR set to a non-numeric string other than `randr`, including values with unit suffixes, locale decimal commas, or stray whitespace/quotes.

Common situations: Copy-pasted config snippets with placeholders; locale-formatted numbers ('1,5'); typos like 'randrr'.

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 normal 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/f1a2040d69c43dfc. Report an issue: GitHub.