How do I fix VAST-2.0-root-version?

Add a `version` attribute to the opening ` ` tag — e.g. ` `.

VAST-2.0-root-version

<VAST> must have a version attribute

ErrorRequired fieldsIAB VAST 2.0 §2.1VAST 2.0 and later (all versions)

The `<VAST>` element must carry a `version` attribute. Without it, players cannot determine which spec version to apply and will usually discard the response.

How to fix

Add a version attribute to the opening <VAST> tag — e.g. <VAST version="4.1">.

Invalid

<VAST>
  <Ad id="1">…</Ad>
</VAST>

Valid

<VAST version="4.1">
  <Ad id="1">…</Ad>
</VAST>

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Other Required fields rules

VAST-2.0-root-elementRoot element must be <VAST>VAST-2.0-root-version-valueVAST version attribute must be a recognised version string VAST-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>VAST-2.0-inline-impression<InLine> must contain at least one <Impression>