Enter a valid traffic estimate
Webmaster site input rejected the traffic field (webmaster-site-input) as not a valid non-negative integer.
Why this happens
Empty junk, negative values, or non-numeric text in the traffic estimate. Distinct from “traffic estimate is too large” (over max).
Diagnose and fix
1. Enter digits only (or leave empty if optional).
2. Use a reasonable monthly/visitor estimate; avoid negatives.
3. Retry add website.
4. See Category contains invalid characters / Could not add website for other field errors.