What does the VAST error " missing required width or height attributes" mean?

The `width` and `height` attributes on ` ` (inside ` `) are required across all VAST versions — 2.0 through 4.2 and 4.3. They tell the player how much space to reserve and which rendition to select. A ` ` element without both attributes will typically be ignored or cause layout failures. In VAST 4.2, the spec explicitly lists `width` and `height` as required attributes of the ` ` element structure inside ` `.

VAST-2.0-nonlinear-dimensions

Q: How do I fix VAST-2.0-nonlinear-dimensions?

Add `width` and `height` attributes to every ` ` element inside ` ` — for example `width="480" height="70"`. Both attributes are required by the IAB VAST spec from version 2.0 through 4.2 and 4.3. Without them most players will ignore or misrender the overlay.

<NonLinear> missing required width or height attributes

WarningAmbiguousIAB VAST 2.0 §2.4.3 / VAST 4.2 §2.4.3VAST 2.0 and later (all versions)

The `width` and `height` attributes on `<NonLinear>` (inside `<NonLinearAds>`) are required across all VAST versions — 2.0 through 4.2 and 4.3. They tell the player how much space to reserve and which rendition to select. A `<NonLinear>` element without both attributes will typically be ignored or cause layout failures. In VAST 4.2, the spec explicitly lists `width` and `height` as required attributes of the `<NonLinear>` element structure inside `<NonLinearAds>`.

How to fix

Add width and height attributes to every <NonLinear> element inside <NonLinearAds> — for example width="480" height="70". Both attributes are required by the IAB VAST spec from version 2.0 through 4.2 and 4.3. Without them most players will ignore or misrender the overlay.

Invalid

<NonLinearAds>
  <!-- ❌ width and height attributes are missing -->
  <NonLinear>
    <StaticResource creativeType="image/gif">
      <![CDATA[https://example.com/overlay.gif]]>
    </StaticResource>
  </NonLinear>
</NonLinearAds>

Valid

<NonLinearAds>
  <!-- ✅ width and height are present -->
  <NonLinear width="480" height="70">
    <StaticResource creativeType="image/gif">
      <![CDATA[https://example.com/overlay.gif]]>
    </StaticResource>
  </NonLinear>
</NonLinearAds>

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Other Ambiguous rules

VAST-3.0-progress-offset<Tracking event="progress"> requires an offset attribute VAST-3.0-icon-attrsIcon missing recommended attributes (program/width/height/position)VAST-2.0-companion-dimensions<Companion> missing width or height VAST-4.0-wrapper-clickthrough<ClickThrough> inside Wrapper <VideoClicks> was removed in VAST 4.0 (re-allowed in 4.2)VAST-4.2-icon-fallback-image-width-height<IconClickFallbackImage> should have width and height attributes VAST-2.0-linear-tracking-quartiles<Linear> has no standard quartile tracking events — measurement system receives no signal