VAST error codes / Ad type and trafficking
VAST error 203: Expecting different size
Short answer: The creative dimensions do not match the expected size.
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
203· Media player expecting different size.
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 player expected creative of a particular size and the response did not provide it.
Common causes
- Media file or companion dimensions outside the accepted range
- Missing width/height so the player cannot size the creative
How to fix it
Check the dimensions on `<MediaFile>`, `<Companion>`, or `<NonLinear>` against the placement.
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-mediafile-dimensions: <MediaFile> must have width and height attributes
- VAST-2.0-companion-dimensions: <Companion> missing width or height
- VAST-2.0-nonlinear-dimensions: <NonLinear> missing required width or height attributes
Related error codes
- VAST error 200: Trafficking error
- VAST error 201: Expecting different linearity
- VAST error 202: Expecting different duration
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