getzola/zola · error

op={} requires a `width` and `height` argument

Error message

op={} requires a `width` and `height` argument

What it means

For `scale`, `fit`, and `fill` operations, both a target width and height are required because these produce exact-dimension outputs. `ResizeOperation::from_args` throws this error when either `width` or `height` is `None` for one of these ops.

Source

Thrown at components/imageproc/src/ops.rs:43

impl ResizeOperation {
    pub fn from_args(op: &str, width: Option<u32>, height: Option<u32>) -> Result<Self> {
        use ResizeOperation::*;

        // Validate args:
        match op {
            "fit_width" => {
                if width.is_none() {
                    return Err(anyhow!("op=\"fit_width\" requires a `width` argument"));
                }
            }
            "fit_height" => {
                if height.is_none() {
                    return Err(anyhow!("op=\"fit_height\" requires a `height` argument"));
                }
            }
            "scale" | "fit" | "fill" => {
                if width.is_none() || height.is_none() {
                    return Err(anyhow!("op={} requires a `width` and `height` argument", op));
                }
            }
            _ => return Err(anyhow!("Invalid image resize operation: {}", op)),
        };

        Ok(match op {
            "scale" => Scale(width.unwrap(), height.unwrap()),
            "fit_width" => FitWidth(width.unwrap()),
            "fit_height" => FitHeight(height.unwrap()),
            "fit" => Fit(width.unwrap(), height.unwrap()),
            "fill" => Fill(width.unwrap(), height.unwrap()),
            _ => unreachable!(),
        })
    }
}

/// Contains image crop/resize instructions for use by `Processor`
///

View on GitHub (pinned to 61d3082821)

Solutions

  1. Supply both `width` and `height` arguments for scale/fit/fill
  2. Or switch to `fit_width`/`fit_height` if only one dimension should constrain the result
  3. Add pre-validation that checks both dimensions exist before selecting these ops

Example fix

// before
image_resize(op="fit", width=300)
// after
image_resize(op="fit", width=300, height=200)
Defensive patterns

Strategy: validation

Validate before calling

function validateResize(op, width, height) {
  const bothRequired = ["scale", "fit", "fill"].includes(op);
  if (bothRequired && (width == null || height == null)) {
    throw new Error(`op=${op} requires width and height`);
  }
  if (width == null && height == null) {
    throw new Error("resize needs at least one dimension");
  }
}

Type guard

fn has_both_dimensions(width: Option<u32>, height: Option<u32>) -> bool {
    width.is_some() && height.is_some()
}

Try / catch

match ResizeOperation::from_args(op, width, height) {
    Ok(op) => apply(op),
    Err(e) if e.to_string().contains("width and height") => {
        log::error!("op {op} needs both dimensions");
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Using `op="scale"`, `op="fit"`, or `op="fill"` with only one of width/height supplied (or neither).

Common situations: Template or config copy where one dimension was deleted; form/URL query strings where a dimension parameter is conditionally absent; switching from fit_width to fill without adding height.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of getzola/zola@61d3082821 (2026-09-03). Data as JSON: /api/errors/6cbc1a0a6965cda0. Report an issue: GitHub.