VAST Error Code List - Simple Guide + Quick Fixes

If you’re seeing VAST errors in a player (or in your ad server logs), you don’t need to memorize the spec to fix them.

This guide is a simple, practical lookup for the most common VAST error codes (plus a few widely-seen Google IMA codes). You’ll learn what the code usually means and the fastest things to check first.

Want to debug quickly? Paste your tag into our VAST Tag Tester to validate the XML, follow wrappers, and inspect media files.

How to use this guide (fast)

Find the error code in your player logs (or the errorcode macro ping).
Jump to the matching section below (use Cmd+F / Ctrl+F).
Do the “Quick checks” in order — they’re sorted from most common to most actionable.

The #1 rule

Most “mystery” VAST errors come down to one of these:

Broken XML (bad characters, unclosed tags, wrong VAST version)
Wrapper chain issues (timeouts, too many hops, or no final inline ad)
Media file problems (404, slow CDN, unsupported codec/MIME)
Player policies (autoplay restrictions, mixed content, sandbox/CORS)

Quick fixes checklist (do these before deep-diving)

Validate the XML: well‑formed, correct encoding, correct VAST version.
Unwrap wrappers: confirm the chain ends in an InLine with a playable <MediaFile>.
Open the media file URL in a browser: confirm it loads and plays.
Check HTTPS everywhere: avoid mixed content (HTTPS page loading HTTP assets).
Verify CORS (especially for IMA / web players): ad tag + media + tracking URLs.
Provide multiple media files: at least one widely compatible MP4 (H.264/AAC) is a good baseline.

100–102: XML & VAST version problems

These mean the player couldn’t read or accept the VAST response.

Code	What it means	Quick checks
100	XML parsing failed	Validate XML, fix unclosed tags, remove invalid characters, confirm encoding.
101	Schema/spec validation failed	Check required nodes/attributes, confirm the response matches its declared VAST version.
102	VAST version not supported	Output a lower VAST version, or upgrade the player/SDK.

200–206: Trafficking / player expectation issues

These mean the player received an ad response that doesn’t match what it requested or can display.

Code	What it means	Quick checks
200	Trafficking error / unexpected ad type	Confirm the slot is a video slot and you’re returning a video-capable response.
201	Incorrect linearity	Ensure the placement expects linear vs non-linear and the response matches.
202	Incorrect duration	Confirm ad duration constraints in the request/pod settings; ensure your creative matches.
203	Incorrect size	Confirm creative dimensions match the slot (or that the player supports scaling).
204	Missing ad category	Add required category metadata if the publisher requires it.
205	Blocked ad category	The inline ad category violates wrapper restrictions; adjust category or targeting.
206	Ad break shortened	Pod/placement changed; verify pod rules and fallback logic.

300–304: Wrapper (redirect chain) problems

Wrappers are powerful, but they’re the source of many “works in one player, fails in another” issues.

Code	What it means	Quick checks
300	General wrapper error	Unwrap manually and check each hop; look for the first bad response.
301	Wrapper URI timeout	Check partner latency, lower wrapper depth, confirm the wrapper URL responds fast.
302	Wrapper limit reached	Too many hops or a loop; remove intermediaries and check for circular redirects.
303	No VAST response after wrappers	One hop returns empty/invalid; verify each wrapper URL returns a valid response.
304	Ad display timeout	Media too slow; optimize file size/bitrate, improve CDN, confirm URLs are reachable.

400–411: Linear / media file playback problems

These usually mean the player found a media file but couldn’t fetch or play it.

Code	What it means	Quick checks
400	General linear error	Check player logs for the real cause; test on another device/player for comparison.
401	Media file not found	URL typo or removed asset; confirm HTTP 200 and correct path.
402	Media file timeout	Large file or slow CDN; compress, reduce bitrate, use a faster edge/CDN.
403	No supported media file found	Provide a compatible MP4 (H.264), correct `<MediaFile type>`, add fallbacks.
405	Media file exists but can’t be displayed	Codec/MIME mismatch, unsupported delivery method, corrupted file; verify headers and playback.
406	Mezzanine required but missing	Provide mezzanine if required by SSAI/publisher.
407	Mezzanine still downloading/transcoding	Wait for ingest/transcode, or provide a pre-transcoded alternative.
408	Conditional ad rejected (deprecated)	Update to modern VAST handling; avoid deprecated conditionalAd usage.
409	Interactive unit not executed	Confirm player supports interactive creatives; verify the creative file and permissions.
410	Verification unit not executed	Check verification script URLs and vendor integration; confirm scripts are reachable.
411	Mezzanine doesn’t meet spec	Re-encode to required format/bitrate/resolution; confirm publisher specs.

500–503: NonLinear ad problems

These are overlay/non-linear creatives that failed to load or fit.

Code	What it means	Quick checks
500	General non-linear error	Verify the non-linear creative is supported and properly configured.
501	Non-linear dimensions mismatch	Resize assets to fit the overlay area; supply multiple sizes.
502	Non-linear resource fetch failed	Check resource URL, CDN, and network policies.
503	Unsupported non-linear resource type	Provide supported resource types and add fallbacks.

600–604: Companion ad problems

Companions are the “sidecar” creatives that show alongside video.

Code	What it means	Quick checks
600	General companion error	Confirm companion slots exist and the player supports companions.
601	Companion dimensions mismatch	Use the correct companion sizes for the page layout.
602	Required companion not displayed	Ensure the page has a companion container; verify requirements and rendering logic.
603	Companion resource fetch failed	Check URL reachability and CDN performance.
604	Unsupported companion resource type	Provide supported resource types (image/HTML) and add fallbacks.

900–902: Unknown / interactive / VPAID issues

These are often environment-specific and require logs.

Code	What it means	Quick checks
900	Undefined error	Check player console logs; validate XML and media; test in another player.
901	General VPAID error	VPAID is fragile; verify sandbox/iframe policies and consider standard VAST instead.
902	InteractiveCreativeFile error	Confirm the file format and that the player supports interactive creatives.

Common Google IMA SDK codes (1000+)

If you’re using Google IMA, you may see SDK-specific codes that are not part of the core IAB VAST error list.

Code	What it means	Quick checks
1005	Ad request failed (often CORS)	Confirm CORS headers for the ad tag, wrappers, media files, and trackers.
1007	Media asset not found/supported	Provide mobile-friendly formats; ensure the right creative targets the right device.
1009	Empty VAST response / expected no-fill	Compare error rate to fill rate; ensure you have fallback demand.
1010	Unknown/malformed response	Validate XML, inspect the raw response, confirm server isn’t truncating content.
1011	Unsupported locale	Check the IMA SDK locale configuration and set a supported locale.
1012	Request blocked / network error	Look for malformed XML or blocked requests; check network filters.
1013	Invalid ad tag URL	Ensure URL is correctly encoded (especially query params and macros).
1020	Stream initialisation failed (SSAI)	Verify stream/SSAI configuration; check SSAI provider logs.
1021	Asset fallback returned no ad	Ensure fallback line items are active and there’s enough demand in the fallback chain.
1101	Invalid arguments in SDK request	Check IMA integration code; verify SDK method params and request options.
1105	Invalid AdX extension	Review GAM/AdX extensions in the response; contact platform support if needed.
1205	Browser prevented playback (autoplay)	Require user interaction or use muted autoplay where allowed.
2025	Display object error	Review player/IMA integration and rendering container setup.
2032	URL access blocked	Check firewall, allowlists, SafeBrowsing/ad-block rules.
2035	Incorrect path to assets	Verify asset URLs and relative/absolute paths in the creative.
2036	Flash ad failed to load	Flash is deprecated; replace with HTML5 / standard video formats.
2048	CORS / mixed-content security violation	Ensure HTTPS for all ad assets and redirects; remove HTTP calls on HTTPS pages.

Why do I see different error codes in different players?

Players and SDKs don’t all report errors the same way. Some map issues to generic codes, and some (like IMA) add their own error ranges.

What’s the fastest way to diagnose wrapper errors?

Unwrap the chain and find the first hop that’s slow, empty, or invalid. Wrapper depth and timeouts are the top causes of 3xx errors.

What’s the fastest way to diagnose 4xx media issues?

Open the <MediaFile> URL directly, confirm it plays, then verify MIME type, codec, and HTTPS/CORS policies.

Next step: test your tag end-to-end

If you want a faster workflow, use our VAST Tag Tester to validate the XML, follow wrappers, and spot media/codec issues before they impact delivery.