VAST Error 301: Wrapper timeout
A wrapper hop took too long to respond and the player gave up — the chain is too slow, not broken.
Players enforce a time budget for resolving VAST redirects — commonly 5 seconds per hop and often a total budget for the whole chain. Error 301 fires when a hop (or the accumulated chain) exceeds it.
Slow chains are the silent revenue killer: unlike a hard failure, the same chain fills fine when the network is fast and times out when it isn't, so 301 shows up as a fluctuating loss rate that tracks load and geography.
Why error 301 happens
Too many sequential hops
Each hop adds a full network round trip plus server decisioning time. Five hops at 800ms each blows a 4-second budget before the ad ever arrives.
One slow intermediary
A single hop doing slow auction decisioning (or calling out to its own demand synchronously) consumes most of the budget on its own.
Geographic distance
A chain that ping-pongs between continents adds hundreds of milliseconds per hop. Users far from the ad servers time out first.
Player budget stricter than the chain assumes
CTV SDKs and SSAI stitchers often enforce tighter timeouts than desktop web players. A chain tuned for web fails on TV.
How to fix VAST error 301
- 1
Measure per-hop latency
Resolve the chain with a validator that reports each hop's response time. The budget-eater is usually one obvious hop, not uniform slowness.
- 2
Flatten the chain
Every intermediary that only re-brokers demand is a candidate for removal. Ask partners for direct tags; each removed hop returns a round trip to the budget.
- 3
Escalate the slow hop with data
Send the slow partner their measured p95 latency. Ad servers can usually tune decisioning or move it to a closer region.
- 4
Monitor from multiple regions
A chain that is fast from your office may be slow from your audience's geography. Test from where your users actually are.
Seeing error 301 on a live tag?
Paste the tag URL or XML — the validator resolves the full wrapper chain, validates the schema, downloads every media file, and shows exactly which stage fails.
Validate your VAST tagVAST error 301 — frequently asked questions
What timeout do players actually enforce?+
It varies: many web players default to around 5 seconds per wrapper request, CTV SDKs are often stricter, and SSAI stitchers enforce total pod-assembly budgets. Design chains to resolve well under 2–3 seconds total to be safe everywhere.
Why does my 301 rate spike in the evening?+
Peak traffic slows every server in the chain simultaneously. Chains that sit near the timeout threshold at quiet hours tip over it under load — a classic sign the chain has no latency headroom.
Is error 301 related to HTTP 301 redirects?+
No. VAST error 301 is a timeout code defined by the VAST spec; HTTP 301 is a permanent-redirect status. Same number, unrelated meanings.