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Common VAST Error Codes and How to Resolve Them

VAST error codes have disrupted video ad serving and left publishers with important time lost. Here are some common VAST errors and their resolution.

VAST error codes continue to disrupt publishers’ experience as they try to leverage video advertising for increasing revenue.

Whether or not to experiment with video advertising  has almost become an outdated question for a publisher. In order to maximise their revenue, publishers must focus on experimenting with programmatic video advertising, 

According to Cisco, 82% of the entire consumer internet traffic will be online videos by the end of 2022. It is evident that users consume video content more than other forms, giving publishers the opportunity to insert ads in between. 

But video advertising comes with its own set of challenges. Despite the technological advancements made in measuring a video ad’s performance, publishers still face error messages in VAST. These VAST error codes are mostly cryptic in nature and render publishers with important time lost. 

If publishers want their video advertising campaigns to succeed, understanding how to interpret and resolve VAST errors is important. 

What is a VAST error?

A VAST error can occur due to a number of reasons and is reported back in case any issue takes place. Ideally, after the code is served for a video ad, the user should be served with that particular ad. However, if the code served request leads to a VAST error, the issue is reported with a numerical code. 

On the basis of the type of VAST error that is reported, the video ad may or may not be served to the user. If the error reported back comes under the ‘non-fatal’ category, then the video player may still play the ad. On the other hand, a ‘fatal’ error will cause the video player to either request for another ad or abort the failed ad request. 

The table below classifies which VAST errors are fatal and which are non-fatal.

Here are some common VAST errors and how publishers can resolve them:

Common VAST Error Codes and Their Resolution

VAST Error 301

This error stands for Timeout of VAST URI. This VAST error normally indicates timeout of an unresponsive or faulty URI inside a VAST creative. However, ad tech experts have often associated a poor network connection or a very high level of latency as the primary causes for this error. 

To resolve this error, publishers can look at a few possible options:

  1. Check the validity of the VAST URI. In most cases, this error occurs because of an unreachable or invalid URI. Checking and making sure that the URI becomes reachable and without faults should resolve the error.

  2. Checking the internet connection can also be a possible solution for this problem. Most likely due to a faulty internet, the request time out occurs. 

  3. Checking protocol issues can also resolve this issue. Sometimes, the URI is being hosted on HTTP but being served on HTTPS. 

VAST Error 302

This VAST error is displayed when the wrapper limit has been exceeded. The video player of the ad often has a pre-defined wrapper limit. Whenever that limit is reached, this error is likely to occur. This can happen if there are too many wrapper responses that have been received, but there is no inline response. Some other possible causes are the existence of daisy chaining (explained in the resolution for this error), empty VAST responses, and others. 

Publishers can possibly resolve this by the following solutions:

  • To accommodate the creatives, buyers can work with SSPs or publishers to increase the wrapper limit. 
  • Avoid daisy chaining which is the process in which ad calls are passed from one network to another. This can cause too many redirects from a video player before an actual media file makes a return, making the video player abort any ad request. 

VAST Error 303

This error generally occurs when an empty VAST response is returned. It is a common error when the ad request is generally contained within a third-party wrapper. Here’s how to resolve this:

Third-party networks often offer a fill rate of less than 100%. To assume the percentage of times that this error can occur, just consider the leftover % of the fill rate. For example, if the fill-rate promised by your third-party network is 60%, there is a 40% chance of this error occurring. The best way for publishers to resolve this is by enabling fallback in Google Ad Manager. This can be enabled by:

  • Sign in to your Google Ad Manager account. 
  • Click on Admin >> Video >> Video Settings
  • Enable Video Fallback
  • Click on Save

VAST Error 402

This error generally stands for a timeout that occurs when a media file is problematic. When the ad creative takes a lot more time than usual to load, then this error occurs. Normally the VAST ad unit contains a creative that has issues such as large size, incompatibility of the platform it is trying to serve at. This can be resolved in the following ways:

  • Publishers can increase their page load speed by optimizing their website layouts. This can be done by partnering with an ad network (like AdPushup). 
  • Another possible solution is increasing the video player’s timeout limit. 
  • Adjusting the bitrate for serving on mobile can also solve this error.

Bonus: General VPAID Error

While this is a VPAID error, if video advertising is being considered, this is one of the most common errors that publishers come across. It is also known as Error 901 and often leaves publishers confused because it can have many different causes. Some of the possible causes are:

  • An IMA Adapter Tag in Ad Exchange is used with the IMA SDK, but a VPAID ad is returned instead. Error 901 will be a fatal error here.
  • VPAID wrapper timeout.
  • VPAID wrapper is not buying video files.

Though the causes can be more than the above listed ones, there are some solutions on how to resolve this error. Publishers need to make sure that whichever VPAID creatives they are using are supported across all devices and video players. Whether or not a VPAID creative is eligible to serve can be checked in Google Ad Manager. Here’s how to do it:

  • Sign in to your Google Ad Manager account.
  • Click on Video >> Video Creative Profiles >> New Video Creative Profile.
  • Configuration for the video creative profile is required. The criteria for this include Name, Restrictions, Bitrate, and Resolution. Setting bitrate is optional. Additionally, under Restrictions, if publishers are allowing VPAID, and a VPAID creative is served, setting a bitrate becomes redundant as ads at any possible bitrate can serve.
  • Click on Save

Also Read: What is Log Level Data and Why Publishers Would Need It?

A List of All the VAST Error Codes

Even though we have already covered the most commonly occurring VAST error codes, there are a plethora of others as well. Here’s a list of all VAST errors and what they mean:

VAST Error CodeCode DescriptionPossibility of Fatability
100XML Parsing ErrorYes
101VAST Schema Validation ErrorYes
1o2VAST version of response not supportedYes
200Trafficking ErrorMaybe
201Video player expecting different linearityMaybe
202Video player expecting different durationMaybe
203Video player expecting different sizeMaybe
300General Wrapper errorYes
301Timeout of VAST URIYes
302Wrapper limit reachedYes
303Empty VAST responseYes
400General linear error. Video player is unable to display the linear ad.Yes
401Unable to find Linear/MediaFile from URIYes
402Timeout of MediaFile URIYes
405Problem displaying MediaFileYes
500General NonLinearAds errorYes
501Unable to display NonLinear Ad because creative dimensions do not align with creative display area (i.e., creative dimension too large)Yes
502Unable to fetch NonLinearAds/NonLinear resourceYes
503Could not find NonLinearresource with supported typeYes
600General CompanionAds errorMaybe
601Unable to display companion because creative dimensions do not fit within Companion display areaMaybe
602Unable to display Required CompanionMaybe
603Unable to fetch CompanionAds/Companion resourceMaybe
604Could not find Companion resource with supported typeMaybe
900Undefined ErrorYes
901General VPAID ErrorYes

We have picked this information directly from the IAB’s wiki for VAST error codes. For more information, you can read here

Best Practices for Publishers to Follow

While publishers can individually do VAST troubleshooting for these errors whenever they occur, the best solution would be to make sure that these errors never occur. Here are some best practices that publishers can follow:

  • Collaborate with your SSPs, DSPs, ad network, and other partners to consistently improve the performance of your VAST creatives. An ideal scenario would be for the VAST error codes to never occur. This will allow seamless ad serving, resulting in increased revenue. Work with your partners to understand the problems that are incessantly causing these errors. 
  • Always make sure that the DSPs scan the creatives beforehand. This will also benefit them and resolve error-causing issues prior to ad serving.


1. What is VAST?

VAST (Video Ad Serving Template) is a script that allows video players and ad servers to run video ads. VAST further gives publishers control over which ad they want to serve, how long the ad should play for, or if the ad is skippable, among other things. 

2. What is VPAID?

VPAID (Video Player Ad Interface) enables the interaction between video ads units and video ad players. With VPAID, advertisers are able to show interactive or rich media ads to their users, which VAST doesn’t allow. 

3. What are VAST tags? 

VAST tags are essentially no different than third-party ad tags. While the latter are codes for serving display ads, VAST tags are codes that enable the serving of video ads. 

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