VAST error codes / NonLinear and companion
VAST error 502: Cannot fetch NonLinear resource
Short answer: The overlay resource could not be loaded.
Debug this tag now
If you only have a live URL, test it first. If the failure is in the wrapper chain, inspect each hop. Validate resolved XML when you already have the response.
What your player reported
502· Unable to fetch NonLinearAds/NonLinear resource.
Wording from the IAB VAST 4.3 specification error table. Players may shorten or reformat it, but the code is the same.
What it means
The non-linear 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 `<StaticResource>`/`<IFrameResource>`/`<HTMLResource>` URL 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-nonlinear-resource: InLine <NonLinear> must contain at least one StaticResource, IFrameResource, or HTMLResource
Related error codes
- VAST error 500: General NonLinearAds error
- VAST error 501: NonLinear dimensions do not fit
- VAST error 503: No supported NonLinear 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.xml