VAST error codes / Linear and media errors
VAST error 406: Mezzanine required but missing
Short answer: A mezzanine file was required for SSAI but not provided. Introduced in VAST 4.1.
What it means
Server-side ad insertion needed a high-quality mezzanine source to transcode, and the ad did not include one.
Common causes
- `<Mezzanine>` omitted where the SSAI pipeline requires it
How to fix it
Provide a `<Mezzanine>` that meets the platform's spec. 411 covers a mezzanine that is present but invalid.
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 vastlint rules
- VAST-4.1-mezzanine-type: <Mezzanine> missing required type attribute
- VAST-4.1-mezzanine-delivery: <Mezzanine> missing required delivery attribute
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.