VAST error codes / Ad type and trafficking
VAST error 201: Expecting different linearity
Short answer: The player expected a different linearity (linear vs non-linear).
What it means
The player asked for one linearity and got the other; for example, a linear video where an overlay was expected.
Common causes
- Linear creative returned for a non-linear placement
- Non-linear overlay returned where a linear video was expected
How to fix it
Align the creative linearity with the placement configuration.
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
- VAST error 200: Trafficking error
- VAST error 202: Expecting different duration
- VAST error 203: Expecting different size
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.