vastlint

VAST ClickThrough in wrapper: valid in 4.2+, removed in 4.0/4.1

Short answer

<ClickThrough> inside wrapper <VideoClicks> is one of the most version-sensitive VAST behaviors. It was removed in VAST 4.0 and 4.1, then explicitly re-allowed in VAST 4.2. If your wrapper ClickThrough is being ignored, the first thing to check is the VAST version you are actually targeting.

Why this happens

Teams often copy a wrapper pattern across versions without revisiting the spec changes. That creates a subtle mismatch: the XML looks reasonable, but 4.0 and 4.1 players may ignore the wrapper click destination entirely. The inverse problem also happens when teams remove wrapper ClickThrough forever and miss the fact that 4.2 restored it.

This is not usually a parser failure. It is a version-behavior mismatch, which is why it is easy to miss until click performance drops.

Copyable fix example

If you must target VAST 4.0 or 4.1 players, keep the wrapper clean and avoid <ClickThrough> there.

<VAST version="4.1">
  <Ad>
    <Wrapper>
      <AdSystem>Example Ad Server</AdSystem>
      <VASTAdTagURI><![CDATA[https://ads.example.com/final-inline.xml]]></VASTAdTagURI>
      <Impression><![CDATA[https://tracker.example.com/wrapper-imp]]></Impression>
      <Creatives />
    </Wrapper>
  </Ad>
</VAST>

Exact rule pages

Use the right tool for this failure

If you already have the resolved XML, run a pure spec check. If you only have a live tag URL, test that endpoint first. If the failure happens in the wrapper chain, inspect each hop.

Validate this XML →Test this live URL →Inspect this wrapper chain →

Further reading