VMAP-1.0-adbreak-multiple-adsource
VMAP-1.0-adbreak-multiple-adsource
`<AdBreak>` may contain at most one `<AdSource>` element
ErrorVMAPIAB VMAP 1.0.1 §2.3.2VMAP 1.0 (all VMAP documents)
Short answer
The VMAP spec allows at most one <AdSource> per <AdBreak>. Multiple <AdSource> children are a schema violation; only the first may be used by players.
Why this matters in production
This rule is usually a delivery blocker. Many players, SDKs, and ad servers will discard the response or skip the affected creative once this condition is hit. VMAP rules validate the ad break schedule envelope. Malformed break timing, wrong namespace declarations, or invalid AdSource content prevent players from resolving any of the ads in the playlist. Affected scope: VMAP 1.0 (all VMAP documents).
Check your VAST tag for
VMAP-1.0-adbreak-multiple-adsource and other issues instantly.Open the VAST tag validator →Other VMAP rules
VMAP-1.0-root-versionRoot `<VMAP>` element must have a version attributeVMAP-1.0-root-version-value`<VMAP>` version attribute should be `"1.0"` — the only published VMAP versionVMAP-1.0-root-namespace`<VMAP>` should declare the VMAP namespace URI http://www.iab.net/videosuite/vmapVMAP-1.0-root-unknown-child`<VMAP>` may only contain `<AdBreak>` and `<Extensions>` elementsVMAP-1.0-adbreak-timeoffset`<AdBreak>` must have a timeOffset attributeVMAP-1.0-adbreak-timeoffset-format`<AdBreak>` timeOffset must be hh:mm:ss[.mmm], n%, `"start"`, `"end"`, or #mVMAP-1.0-adbreak-breaktype`<AdBreak>` must have a breakType attributeVMAP-1.0-adbreak-breaktype-value`<AdBreak>` breakType must be a comma-separated list of `"linear"`, `"nonlinear"`, or `"display"`