vastlint
VAST-4.1-interactive-creative-type

VAST-4.1-interactive-creative-type

<InteractiveCreativeFile> should have a type attribute identifying the MIME type

WarningRequired fieldsIAB VAST 4.1 §2.4.1VAST 4.1, 4.2, and 4.3

Short answer

The type attribute on <InteractiveCreativeFile> should carry a MIME type so players can determine how to handle the file.

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. 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 4.1, 4.2, and 4.3.

How to fix

Add type="application/javascript" (or the correct MIME type) to <InteractiveCreativeFile>.

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