VAST errors: all 38 error codes and how to fix them

Why this happens

Most players expose only a coarse numeric code because they do not ship a full validator or a structured diff of the XML they received. That means one code can hide several concrete failures: a missing wrapper URL, a malformed media URL, a deprecated VPAID creative on CTV, or a chain that never resolves inline.

The practical workflow is: use the runtime code to narrow the class of failure, then use the validator, tester, or inspector to find the exact broken element.

Common codes and likely root causes

Copyable fix example

A large share of player-side wrapper errors collapse down to one XML problem: the wrapper does not actually point to the next VAST response.

<!-- Copy this wrapper fix when the chain must continue -->
<VAST version="3.0">
  <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>

<!-- Copy this wrapper fix when the chain must continue -->
<VAST version="3.0">
  <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

• VAST-2.0-wrapper-vastadtaguri
• VAST-2.0-wrapper-depth
• VAST-2.0-mediafile-url
• VAST-2.0-duration-format
• VAST-4.1-vpaid-in-interactive-context

Look up the message your player printed

Players surface the IAB wording rather than a plain-English explanation, so this is the table to scan if you have a message but no idea which code it belongs to. Every row is the verbatim description from the VAST 4.3 specification.

Not seeing your message? Player SDKs wrap these in their own text. A Video.js log line like [error] (101): Failed to load VAST is still error 101, and Failed to load VAST on its own is usually 100, 101, or 301, depending on whether the response was unparseable, structurally invalid, or never arrived.

Every VAST error code

Each code has a dedicated page with its likely causes, the fix, and the exact vastlint rules that catch it before launch.

Further reading

• Common VAST errors and how to fix them
• VAST tag testing guide
• Wrapper depth exceeded