VASTlint
VAST-2.0-macro-unknown

VAST-2.0-macro-unknown

URL contains a [MACRO] that is not a recognised IAB VAST macro

WarningMacrosIAB VAST 4.2 §6VAST 2.0 and later (all versions)

Short answer

A [TOKEN] in a tracking, click, error, impression, or media URL does not match any macro in the IAB VAST macro list. Most often this is a typo (for example [CACHEBUSTNG]) that the player will never substitute, leaving the literal text in the request. If it is a deliberate vendor-specific macro, disable this rule.

Why this matters in production

This rule is a strong risk signal. Tags with this issue often still parse, but they become brittle across SDKs, SSAI resolvers, and CTV environments. Macro rules catch substitution problems in tracking, click, and error URLs. A misspelled, mis-cased, or out-of-context macro is never replaced by the player, so the server receives literal placeholder text instead of the measurement value, and unencoded characters can break the request entirely. Affected scope: VAST 2.0 and later (all versions).

Invalid

<Impression><![CDATA[https://t.example.com/i?cb=[CACHEBUSTNG]]]></Impression>

Valid

<Impression><![CDATA[https://t.example.com/i?cb=[CACHEBUSTING]]]></Impression>
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