Structured User Agent has no browsers
device.sua is present but browsers is missing or empty, so it cannot replace device.ua.
What it means
UserAgent.browsers is recommended: an array of BrandVersion objects, each with a required brand. An empty sua object is a structured UA with no brands.
Why it matters
CHIPS and UA reduction make device.ua unreliable. sua is the replacement. Empty browsers means the structured path carries nothing, and buyers fall back to a reduced ua string or skip device targeting.
How to fix it
Populate browsers with at least one BrandVersion (brand required, version optional). platform is the OS BrandVersion.
Example that trips it
{ "device": { "ua": "Mozilla/5.0", "sua": {} } }Check your payload
Paste a bid request or response into the tester to see whether this code fires against it, or gate on the id in CI with the CLI: the id is stable, wording is not.
Back to the full diagnostic code reference.