VAST error codes / Wrapper errors
VAST error 304: Inline displayed too slowly
Short answer: An inline ad resolved but did not display within the time limit. Introduced in VAST 4.0.
What it means
The chain produced an inline ad, but rendering did not complete inside the player's defined window.
Common causes
- Heavy creative or slow media that exceeds the display deadline
- Late-resolving assets in the inline ad
How to fix it
Profile the inline creative's load time and trim wrapper latency so the inline ad has time to render.
VAST error codes are runtime buckets emitted by the player. They tell you where the failure happened, not which line of XML caused it. Paste the raw tag into the validator to map this code onto the exact element and rule.
Related error codes
Debug this tag now
Validate the XML, follow the wrapper chain, or check it in CI before launch:
# CLI: exits non-zero on errors, ideal for pipelines
vastlint check creative.xmlUse 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.