VAST-4.1-blockedadcategories-authority-unknown
<BlockedAdCategories> authority is not a recognised IAB Content Taxonomy authority
Short answer
The authority value is well-formed but not an IAB Content Taxonomy registry host. Block lists under a private taxonomy only take effect if the downstream ad server resolves the same authority; using the IAB taxonomy makes the block list portable across the chain.
Why this matters in production
This rule is advisory rather than fatal, but it still matters for portability, debugging speed, and keeping tags predictable across different buyers and playback stacks. Value-format rules tend to fail at the moment a player interprets a field such as duration, skipoffset, bitrate, or versioning. They are especially painful because the XML can look valid at a glance. Affected scope: VAST 4.1, 4.2, and 4.3.
Invalid
<BlockedAdCategories authority="blocklist.example.org">IAB25</BlockedAdCategories>Valid
<BlockedAdCategories authority="iabtechlab.com">IAB25 IAB26</BlockedAdCategories>VAST-4.1-blockedadcategories-authority-unknown and other issues instantly.Open the VAST tag validator →