vastlint
VAST-2.0-companion-resource

VAST-2.0-companion-resource

<Companion> must contain at least one StaticResource, IFrameResource, or HTMLResource

ErrorRequired fieldsIAB VAST 2.0 §2.4.2VAST 2.0 and later (all versions)

Short answer

A <Companion> element must carry at least one resource that can actually be rendered: <StaticResource>, <IFrameResource>, or <HTMLResource>. An empty companion is not valid.

Why this matters in production

This rule is usually a delivery blocker. Many players, SDKs, and ad servers will discard the response or skip the affected creative once this condition is hit. Required-field failures usually stop validation early because the platform cannot determine the basic shape of the ad, the creative metadata, or the mandatory tracking payload. Affected scope: VAST 2.0 and later (all versions).

How to fix

Add <StaticResource>, <IFrameResource>, or <HTMLResource> inside each <Companion> to supply the renderable asset.

Invalid

<Companion width="300" height="250">
  <!-- no resource -->
</Companion>

Valid

<Companion width="300" height="250">
  <StaticResource creativeType="image/png">
    <![CDATA[https://cdn.example.com/companion.png]]>
  </StaticResource>
</Companion>
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Other Required fields rules

VAST-2.0-root-elementRoot element must be <VAST>VAST-2.0-root-version<VAST> must have a version attributeVAST-2.0-root-version-valueVAST version attribute must be a recognised version stringVAST-2.0-root-has-ad-or-error<VAST> must contain at least one <Ad> or <Error>VAST-4.0-wrapper-root-error<VAST> root contains both <Ad> and <Error> elements (invalid per VAST 4.0)VAST-2.0-ad-has-inline-or-wrapperEach <Ad> must contain exactly one <InLine> or <Wrapper>VAST-2.0-inline-adsystem<InLine> must contain <AdSystem>VAST-2.0-inline-adtitle<InLine> must contain <AdTitle>