VAST error codes / NonLinear and companion
VAST error 603: Cannot fetch companion resource
Short answer: The companion resource could not be loaded.
What it means
The companion resource URL did not resolve to a usable asset.
Common causes
- Broken resource URL
- HTTP resource blocked on an HTTPS page
How to fix it
Confirm the companion `<StaticResource>`/`<IFrameResource>`/`<HTMLResource>` is reachable over HTTPS.
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-resource: <Companion> must contain at least one StaticResource, IFrameResource, or HTMLResource
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.