VAST Error 205: Inline category violates wrapper BlockedAdCategories
The resolved ad declares a category that an upstream wrapper explicitly blocked — the ad is rejected and the block is reported upstream.
A wrapper can carry <BlockedAdCategories> naming categories that must not run. If the final inline ad declares one of those categories, the player rejects it with 205 and is expected to notify the wrapper's ad server via its <Error> pixel.
This is the enforcement half of the category system working as designed — demand that should have been filtered upstream reached the player and got caught.
Why error 205 happens
Upstream decisioning ignored the block list
The ad server or exchange that filled the impression didn't filter by the wrapper's blocked categories, letting a blocked-category ad through.
Category mismatch between taxonomies
The block list and the ad use different authorities, so upstream filtering couldn't match them — but the player's stricter comparison catches it.
Miscategorized creative
The ad declares a category it shouldn't (or a broader one than needed), colliding with block rules aimed at genuinely sensitive content.
How to fix VAST error 205
- 1
Identify the blocking wrapper and the violating category
Resolve the chain, list each hop's <BlockedAdCategories>, and compare with the inline ad's <Category>. That tells you which rule fired.
- 2
Push enforcement upstream
The demand path that served the ad should filter blocked categories before responding. Report the violation to the partner — 205 volume is evidence.
- 3
Fix miscategorized creatives
If the ad is wrongly classified, correct the category declaration at the source rather than loosening the block list.
Seeing error 205 on a live tag?
Paste the tag URL or XML — the validator resolves the full wrapper chain, validates the schema, downloads every media file, and shows exactly which stage fails.
Validate your VAST tagVAST error 205 — frequently asked questions
Who gets notified when a 205 fires?+
The player fires the error pixel of the wrapper that declared the violated block list, so the ad server that set the rule learns its filter was bypassed downstream.
Is 205 lost revenue or successful protection?+
Both — the impression went unfilled, but the alternative was running a category the publisher explicitly banned. Reduce it by getting demand partners to respect block lists pre-bid.