# Bad value X for attribute “srcset” on element “img”: Expected single descriptor but found extraneous descriptor Y at Z.

> Canonical HTML version: https://rocketvalidator.com/html-validation/bad-value-x-for-attribute-srcset-on-element-img-expected-single-descriptor-but-found-extraneous-descriptor-y-at-z
> Attribution: Rocket Validator (https://rocketvalidator.com)
> License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Each image candidate in `srcset` is a URL followed by at most one descriptor, such as `800w` or `2x`, so any extra token before the next comma is an error.

Commas separate the candidates in `srcset`. The validator reads each candidate as a URL followed by one width descriptor (`800w`) or pixel density descriptor (`2x`). When a third token turns up, the message names it as the extraneous descriptor, and the part after `at` quotes the stretch of the value that ends with it. Browsers parse `srcset` with the same rules and skip that candidate.

An extraneous descriptor ending in `=`, such as `loading=`, usually means the closing quote of `srcset` is missing. The value runs on into the next attribute and stops at that attribute's opening quote, so `loading=` lands in the candidate list and the browser never sees a `loading` attribute. The validator also reports "No space between attributes" on the same element and rejects `lazy"` as an attribute name. Long values are left out of the message, which then starts with `Bad value for attribute “srcset”`.

If the extraneous descriptor is a file name, a comma is missing between two candidates. If it's a second descriptor, like `2x` after `400w`, keep only one: a candidate takes a width or a density, not both.

## Invalid examples

The closing quote after `800w` is missing, so `loading=` becomes part of the `srcset` value:

```html
<img
  src="photo-400.jpg"
  srcset="photo-400.jpg 400w,
          photo-800.jpg 800w
  loading="lazy"
  sizes="(max-width: 600px) 100vw, 600px"
  alt="A mountain lake at sunrise">
```

Without a comma between the candidates, the second URL reads as a descriptor of the first:

```html
<img
  src="photo-400.jpg"
  srcset="photo-400.jpg 400w photo-800.jpg 800w"
  sizes="(max-width: 600px) 100vw, 600px"
  alt="A mountain lake at sunrise">
```

## Valid example

```html
<img
  src="photo-400.jpg"
  srcset="photo-400.jpg 400w,
          photo-800.jpg 800w"
  loading="lazy"
  sizes="(max-width: 600px) 100vw, 600px"
  alt="A mountain lake at sunrise">
```