VAST error codes / NonLinear and companion
VAST error 601: Companion does not fit
Short answer: No display space for the companion's dimensions.
What it means
The companion creative's dimensions do not fit the available companion slot.
Common causes
- Companion larger than the slot
- Missing or wrong width/height on `<Companion>`
How to fix it
Set `<Companion>` width and height to match an available slot.
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-2.0-companion-dimensions: <Companion> missing width or height
- VAST-3.0-companion-required-attr: <CompanionAds> required attribute must be all, any, or none
Related error codes
- VAST error 600: General CompanionAds error
- VAST error 602: Required companion not displayed
- VAST error 603: Cannot fetch companion resource
- VAST error 604: No supported companion resource
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.