Digital publishers and advertisers have a great deal to lose if they are unable to quickly identify and resolve video ad errors.
Online videos will constitute 82% of internet traffic by the end of 2022, according to the Cisco Annual Internet Report. With publishers able to increase revenue by inserting ads in the middle of the videos and adopting programmatic advertising, successfully interpreting and resolving a VAST error is essential.
The Interactive Advertising Bureau (IAB) introduced the Video Ad Serving Template (VAST) in 2008, streamlining ad serving to a variety of digital video players. VAST Tags, which are pieces of code governed by the XML markup schema, allow video players to understand detailed information about the ad, including its length, format and destination URL.
The introduction of VAST was accompanied by a list of error codes, designed to allow video players to report when ads don't serve as expected. These codes are designed not only to allow publishers and ad servers to troubleshoot problems, but also to influence the development of video advertising technology.
Over the years, the Interactive Advertising Bureau (IAB) has updated and refined its list of VAST error codes.
Table of contents:
VAST error codes and how to resolve them
The IAB launched its latest version of VAST — VAST 4.2 — in June 2019, with the latest specification containing 37 VAST error codes.
Not all of these errors are equally severe, however, and can generally be divided into two categories: “fatal” and “potentially non-fatal”.
Fatal errors are those that stop an ad from being served, either leading to another ad being requested or the resumption of video content playback. A non-fatal error, meanwhile, may lead to some errors that will still allow the ad to play.
Below is a detailed list of the various errors, split into fatal and potentially non-fatal categories, along with advice on how to resolve them.
VAST Error 100 - XML parsing error
This error occurs when either the buyer's response is distorted, an invalid XML document or a redirect VAST URL fails to resolve successfully.
How to resolve VAST error 100: The digital publisher needs to alert the buyer, who must then verify that the VAST XML is correctly formatted and contains all of the required elements and attributes. You can learn more in the VAST specification from .
VAST Error 101 - Schema validation error
This error is caused when either the buyer's response is missing the XML’s instructed elements or attributes, or contains unknown elements.
How to resolve VAST error 101: The digital publisher needs to alert the buyer, who must verify the VAST XML formatting and ensure that it contains all the required elements and attributes.
VAST Error 102 - Response version not supported
This error can be caused when either a video player does not support the bid request’s specified VAST version or the exchange sends the wrong version.
How to resolve VAST error 102: The digital publisher needs to alert the buyer, who must ensure that only supported VAST versions are sent.
VAST Error 300 - Wrapper error
This error is caused when the wrapper limit is reached and is not actionable. However, there are some pre-emptive steps that can be taken.
How to prevent VAST error 300: Conduct a review of all VAST URIs (uniform resource identifier) to ensure they are not timing out and remain reachable, while also ensuring that a wrapper’s limit is not reached.
VAST Error 301 - Redirect timeout reached
This error can be caused when a VAST redirect tag failed to respond or was unavailable within the wrapper’s defined timeout, which is set at five by default. Reasons can include:
- Overly low player timeout setting
- Poor website optimization
- Wrong creative dimension
- Invalid URI or VAST URI request timeout
- High latency connection
- HTTP serving to HTTPS
How to resolve VAST error 301: The publisher can up the video’s player timeout limit, while the buyer must ensure the VAST redirect URI is reachable and that no protocol issues exist.
VAST Error 302 - Wrapper limit reached
This error is caused when the wrapper limit, as defined by the video player, is reached due to either too many empty VAST responses from video fallback, too many wrapper responses have been received without an inline response, or a circular loop of network bounces (daisy chaining) exists.
How to resolve VAST error 302: The publisher needs to increase the player’s wrapper limit, while the buyer needs to check that any VAST redirects don’t redirect again to another network.
VAST Error 303 - Empty VAST response returned
This error occurs when no ads are returned in a VAST response after one or more wrappers and includes empty responses from video fallback.
However, when a third-party network that has set a less than 100% fill rate, unreturned ad requests in the fill rate delta can be considered an expected error.
How to resolve VAST error 303: The publisher needs to check the third-party network fill-rate and can use video fallback to avoid lost impressions. The buyer, meanwhile, can check that bids are not returned with an empty VAST response while also ensuring that the ad creative’s host is not returning empty responses.
Error 400 - General linear error
This error usually occurs when a video player can’t display a linear ad, owing to either an invalid MediaFile format, the browser’s autoplay restriction or an unknown reason.
How to resolve VAST error 400: Publishers have three options here: Check for player issues, enable video player detection for restricted autoplay or contact the buyer. The buyer, meanwhile, must check that the VAST response is returning a valid creative.
Error 401 - MediaFile not found
This error occurs when a file can’t be found from a MediaFile URI.
How to resolve VAST error 401: The publisher’s only recourse here is to alert the buyer, who must ensure that all MediaFile URIs return a valid video creative.
Error 402 - Unable to download or timeout of MediaFile URI
This error occurs when it takes too long to fetch or play a MediaFile and can be caused by either the loadVideoTimeout being set too low, website bandwidth issues and competing request issues that lead to loading delays. The error can also be traced to auto-play issues, such as click-to-play mobile restrictions or showing ads in a playlist while the window is out of focus.
How to resolve VAST error 402: The publisher needs to increase the video player’s timeout limit, while the buyer should check that any CDN-hosted creatives are returned within the specified timeout.
Error 403 - Response declared unsupported MIME types for all MediaFiles
This error is more common on mobile devices and may mean that the wrong creative type attempted to play. It is caused when a VAST response declares unsupported MIME (multipurpose internet mail extensions) types for all available MediaFiles.
How to resolve VAST error 403: Publishers should check that the video player's device and platform supports the creative format. Mobile apps, for instance, should not request VPAID creatives. Buyers need to ensure that all returned creatives respect the bid request’s video format.
Error 405 - MediaFile display error
This error typically occurs when an incorrect creative is returned and can be caused by a MIME-video file type incompatibility, a CORS (cross-origin resource sharing) configuration on the creative’s CDN, or other transcoding-related reasons.
How to resolve VAST error 405: The publisher needs to alert the buyer, who must check all creative MIME types and CDN configurations for accuracy.
Error 406 - Missing required mezzanine file
This error occurs when a VAST response is returned without a required mezzanine file. Publishers that rely on SSAI (server-side ad insertion), or ad-stitching, usually require mezzanine files to generate videos of appropriate quality.
How to resolve VAST error 406: The publisher needs to alert the buyer, who must check all that a mezzanine file is included in the response.
Error 407 - Mezzanine file downloaded for the first time
This error occurs either when a mezzanine file is downloaded for the first time or if an ad insertion is missed owing to creative transcoding.
How to resolve VAST error 407: These are expected outcomes and no action is needed.
Error 408 - Rejected ad in VAST response
This error occurs when the ad returned in the VAST response is rejected.
How to resolve VAST error 408: The publisher needs to alert the buyer, who must ensure that the VAST response only returns approved creatives and that ad creative hosts are aware of rejections.
Error 409 - Interactive creative defined in the InteractiveCreativeFile node did not execute
This error occurs in a creative display area when a creative defined in the InteractiveCreativeFile node does not execute.
How to resolve VAST error 409: The publisher needs to alert the buyer, who must ensure that returned interactive creatives successfully play when requested.
Error 410 - Code referenced in the Verification node did not execute
As the title indicates, this error occurs when the code referenced in the AdVerification node does not execute.
How to resolve VAST error 410: The publisher needs to alert the buyer, who needs to check that the code is being implemented according to the verification vendor’s specifications.
Error 500 - General NonLinearAds error
This error occurs when a video player is unable to display a non-linear ad, though the reason is unknown.
How to resolve VAST error 500: The publisher needs to check for video player issues and then have the buyer review whether the VAST response is returning a valid creative.
Error 501 - Non-linear ad creative dimensions do not align with creative display area
This error occurs when a non-linear ad fails to play as a result of the creative’s dimensions being larger than the creative display area. It may also occur if CSS styles are used to set the video content’s dimensions.
How to resolve VAST error 501: The publisher needs to match the display area’s dimensions, while also ensuring that video content dimensions are set with HTML attributes instead of CSS styles. The buyer’s only option, meanwhile, is to alert the publisher.
Error 502 - Unable to fetch NonLinearAds/NonLinear resource
This error occurs when the buyer's response returns a non-linear ad that fails to return a valid creative.
How to resolve VAST error 502: The publisher needs to alert the buyer, who must ensure that valid creatives are returned.
Error 503 - Could not find NonLinearresource with supported type
This error happens when a creative size is bigger than the player size, or not a proper media type
How to resolve VAST error 503: The publisher needs to check that the video player can accept the requested creative sizes and media types. From the buyer’s side, the only option is to alert the publisher.
Error 901 - General VPAID error
This error can be caused by SSP VPAID wrapper timeout, SSP VPAID wrapper not buying, VPAID creatives required insecure mode, or an IMA Adapter tag is used with the IMA SDK when the Direct SDK tag should have been used.
How to resolve VAST error 901: The publisher needs to ensure that any VPAID creative requests have devices and player support. Video creative profiles can be used to determine which creatives can be served. The buyer must both check that VAST responses that return HTML5 VPAID wrappers from IAS/DV/MOAT include an MP4 asset and that the wrapper is not aborting playback.
Error 200 - Video player expected different ad type
This error is caused when a video player does not support an ad type requested in a bid request. For example, the player requested a Linear ad, but was served Skippable Linear.
How to resolve VAST error 200: The publisher needs to check for trafficking errors or alert the buyer, who must ensure that only specified ad types are sent in a response.
Error 201 - Video player expected different linearity
This error is caused when the buyer's response linearity does not match the video player's request. This can happen when the ad exchange sends the wrong linearity in the bid request or when the bidder doesn’t respect the bid request’s linearity.
How to resolve VAST error 201: The publisher needs to ensure that the ad request’s specified linearity is correct, while the buyer must ensure that the response respects the request.
Error 202 - Video player expected different duration
This error can occur when a returned creative is a different duration than specified.
How to resolve VAST error 202: Publishers need to ensure that the creative duration is appropriately set in Google Ad Manager. Buyers, meanwhile, must ensure that the response respects the max duration specified.
Error 203 - Video player expected different size
This error can occur when returned MediaFiles are incompatible with the target device, such as when high bitrate creatives are returned to mobile devices.
How to resolve VAST error 203: Publishers have to alert the buyers, who are responsible for ensuring their response includes MediaFiles that are compatible with different technologies and devices.
Error 600 - General CompanionAds error
This error is caused when a publisher is unable, for unknown reasons, to display a companion ad.
How to resolve VAST error 600: Publishers need to either check for ad serving issues or alert the buyers, who need to check that the VAST response is returning a valid creative.
Error 601 - Companion creative dimensions did not align with companion display area
This error can happen when the companion creative’s dimensions do not fit within the display area.
How to resolve VAST error 600: Buyers should alert the publishers, as they need to ensure that the requested companion ad size fits the dimension of the ad unit.
Error 602 - Unable to display required companion
This error can occur when the publisher is unable to render the companion ad creative returned in the VAST response.
How to resolve VAST error 602: Publishers need to check for ad serving issues, or alert the buyers, who must ensure that the VAST response returns a valid creative.
Error 603 - Unable to fetch CompanionAds/Companion resource
This error occurs when the buyer's response returns a companion ad that fails to yield a valid creative.
How to resolve VAST error 603: Publishers should alert the buyers, who should check that the response returns valid creatives.
Error 604 - Could not find Companion resource with supported type
This error occurs when a publisher demands an unsupported creative type for the companion ad slot.
How to resolve VAST error 604: Buyers should alert the publishers, who need to ensure that the ad slot supports the specified creative types.
A little bit of both
Error 900 - VAST 2 error (potentially non-fatal)
This error, which is the most common type of 900 error, can be caused when any VAST 2 error occurs. This is the case even if VAST 3 is requested or the network default is set to VAST 3.
How to resolve VAST error 900: The publisher either needs to request VAST 3 or activate VAST 3 for their network. The buyer, meanwhile, can either work with the publisher to troubleshoot the exact issue or respond with VAST 3.
Error 900 - Undefined VAST 3 error (fatal)
This error is much more uncommon and is the result of an unknown VAST 3 error that likely stopped the ad request. This is the only type VAST 900 error that is reported in Google’s creative debugging tool, RTB Breakout.
How to resolve VAST error 900: The publisher and buyer need to work together to troubleshoot the issue.
Best Practices to Follow
Though the best solution is to make sure that these errors don't occur. However, publishers can handle these errors individually, as mentioned above or can keep in mind the best practices to avoid them.
- Always ensure that the DSPs scan all the creatives beforehand. This will save a lot of time and resolve error-causing issues before serving the ad.
- It is always advisable to collaborate with your SSPs, DSPs, ad network, ad servers and other partners beforehand. It helps in improving the performance of your VAST creatives. Thus, allowing seamless ad serving, resulting in increased revenue. In addition, working with your partners to comprehend the problems that are perpetually causing these errors will definitely help in the long run.
Understanding a VAST error is an important aspect that will eventually maximise your video ad performance. Hence, learning about them is vital.
Need help to resolve your VAST Errors?
At Publift, we understand the importance of video advertising and every penny spent on it. Thus, we assist digital publishers in ensuring the VAST Errors don't occur for them and, if they occur, how to resolve them.
If you’re making more than $2,000 in monthly ad revenue, contact us today to learn more about how Publift can help increase your ad revenue and best optimize the ad space available on your website or app.