VAST-2.0-inline-adsystem
VAST-2.0-inline-adsystem
<InLine> must contain <AdSystem>
ErrorRequired fieldsIAB VAST 2.0 §2.3VAST 2.0 and later (all versions)
Short answer
<AdSystem> identifies the ad server that created the response. It is required inside every <InLine> and <Wrapper>. Omitting it violates the VAST spec and may cause auction-level tracking failures.
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 <AdSystem version="1.0">Your Ad Server Name</AdSystem> as a child of <InLine>.
Invalid
<InLine>
<AdTitle>My Ad</AdTitle>
<!-- missing AdSystem -->
</InLine>Valid
<InLine>
<AdSystem version="1.0">My Ad Server</AdSystem>
<AdTitle>My Ad</AdTitle>
</InLine>Check your VAST tag for
VAST-2.0-inline-adsystem and other issues instantly.Open the VAST tag validator →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-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-adtitle<InLine> must contain <AdTitle>VAST-2.0-inline-impression<InLine> must contain at least one <Impression>VAST-2.0-inline-creatives<InLine> must contain <Creatives> with at least one <Creative>