Understanding and Resolving VAST Errors in Digital Video Advertising

Introduction

In the dynamic world of digital video advertising, ensuring smooth ad delivery is paramount. However, technical hurdles, known as VAST Errors, often disrupt this process. VAST, or Video Ad Serving Template, is a standard created by the Interactive Advertising Bureau (IAB) to streamline video ad delivery across various platforms. While VAST revolutionized the industry, it also introduced complexities leading to various errors. Understanding these errors is crucial for publishers and advertisers to optimize ad performance and enhance user experience.

What Are VAST Errors?

VAST Errors arise during the delivery of digital video ads, potentially leading to ads not playing correctly or at all. These issues can stem from technical glitches in ad servers, compatibility problems between players and ads, incorrect VAST tag implementation, or network connectivity issues. The consequences? A poor user experience and decreased ad engagement, impacting both publishers and advertisers negatively.

The Role of the VAST Tag

At the heart of these errors lies the VAST tag. This XML-based code snippet is the communication bridge between ad servers and video players. It carries crucial information about the ad and tracking events, ensuring consistent ad delivery and performance tracking. A well-implemented VAST tag is key to reducing errors and ensuring successful ad campaigns.

Categorizing VAST Error Codes

VAST errors are broadly classified into two categories: fatal and potentially non-fatal. Fatal errors are critical, completely preventing ad playback. Examples include XML parsing errors and issues with unsupported VAST versions. Non-fatal errors, while not stopping the ad from playing, can degrade the ad’s quality or functionality, such as issues with media files or player display errors.

List of All Fatal VAST Errors

XML Parsing Error (Error 100):

• Cause: Invalid XML document in the VAST response or redirect URL issues.
• Solution: Publishers should inform the buyer to correct the XML format based on IAB standards.

VAST Schema Validation Error (Error 101):

• Cause: Missing essential elements or unrecognized elements in the VAST response.
• Solution: Buyers should ensure their VAST XML file adheres to IAB’s specifications.

VAST Version Not Supported (Error 102):

• Cause: Incompatibility between the player and the VAST version.
• Solution: Publishers should inform buyers to include only supported VAST versions in responses.

Wrapper Error (Error 300):

• Cause: Exceeding the maximum limit of wrappers.
• Solution: Review VAST URIs for accessibility and avoid exceeding wrapper limits.

VAST Redirect Timeout (Error 301):

• Cause: Delayed response or inaccessibility of VAST redirect tag.
• Solution: Increase the timeout limit in the player and ensure VAST redirect URI accessibility.

Wrapper Limit Exceeded (Error 302):

• Cause: The wrapper limit set by the video player is exceeded due to too many wrapper responses, daisy chaining, or empty VAST responses.
• Solution: Increase the wrapper limit in the player. Buyers must avoid excessive VAST redirects.

Empty VAST Response Returned (Error 303):

• Cause: No ads returned in a VAST response, common in third-party networks with less than 100% fill rate.
• Solution: Implement video fallback to utilize impressions effectively. Buyers should ensure bids are not returned with an empty VAST response.

Linear Error (Error 400):

• Cause: Issues preventing the display of linear ads, such as invalid media file format or autoplay restrictions.
• Solution: Verify player functionality and buyer’s VAST response for valid creatives.

Media File Not Found (Error 401):

• Cause: The video player cannot locate the required file from a specified MediaFile URI.
• Solution: Publishers should alert the buyer to verify all MediaFile URIs in the VAST response.

Unable to Download MediaFile (Error 402):

• Cause: Issues retrieving or playing the MediaFile, including low timeout settings or poor website implementation.
• Solution: Increase the player’s timeout limit and ensure CDN-hosted creatives return within the media timeout.

Unsupported MIME Types (Error 403):

• Cause: All MediaFiles in the VAST response list unsupported MIME types.
• Solution: Confirm compatibility of creative format with video player’s device and platform.

MediaFile Display Error (Error 405):

• Cause: Faulty creative due to MIME type mismatch, incorrect CDN setup, or transcoding problems.
• Solution: Buyers should verify the creative’s MIME type and CDN configurations.

Missing Required Mezzanine File (Error 406):

• Cause: Absence of a necessary mezzanine file in the VAST response.
• Solution: Ensure inclusion of a mezzanine file in the VAST response when required by the publisher.

Mezzanine File Download Issue (Error 407):

• Cause: Delay in downloading the mezzanine file, preventing ad serving.
• Solution: As this error is expected during the transcoding process, no immediate action is necessary.

Rejected Ad in VAST Response (Error 408):

• Cause: Rejection of the ad returned in the VAST response.
• Solution: Buyers should ensure that only approved creatives are returned or inform advertisers of the rejection.

InteractiveCreativeFile Execution Failure (Error 409):

• Cause: A creative defined in the InteractiveCreativeFile node fails to execute.
• Solution: Publishers should alert buyers to ensure interactive creatives in the VAST response function properly.

Ad Verification Code Non-execution (Error 410):

• Cause: Non-execution of code referenced in the AdVerification node.
• Solution: Publishers must inform buyers to implement the verification code correctly according to the verification vendor’s guidelines.

General NonLinearAds Error (Error 500):

• Cause: Issues with the display of non-linear ads, often due to video player problems or invalid creatives.
• Solution: Publishers should check for video player issues and buyers must verify the validity of the creative.

Non-linear Creative Dimension Mismatch (Error 501):

• Cause: Non-linear ad creative dimensions not aligning with the display area.
• Solution: Ensure ad dimensions match the display area, adjusting CSS styles or HTML attributes as needed.

NonLinear Resource Fetching Issue (Error 502):

• Cause: Failure to deliver a valid creative for non-linear ads.
• Solution: Publishers should alert buyers to ensure valid creatives are returned in the response.

NonLinear Resource Type Mismatch (Error 503):

• Cause: Requesting a creative size or type not supported by the video player.
• Solution: Publishers should only request supported creative types, while buyers should align with these requests.

Undefined VAST 3 Error (Error 900):

• Cause: An unknown issue with VAST 3 stops the ad request.
• Solution: Collaborative troubleshooting between publishers and buyers to identify and resolve the root cause.

General VPAID Error (Error 901):

• Cause: Various VPAID issues such as creative requirements for insecure mode or improper use of IMA Adapter tags.
• Solution: Publishers should ensure support for all VPAID creative requests, while buyers should verify proper VAST response returns and wrapper functionality.

Empty VAST Response Document (Error 1009):

• Cause: The VAST response contains no video files or tracking events.
• Solution: Publishers should check their ad setups for errors, while buyers should alert publishers to any discrepancies.

Potentially Non-Fatal VAST Errors

Different Ad Type Expected (Error 200):

• Cause: The video player is unable to support the ad type requested.
• Solution: Monitor ad trafficking and ensure compatibility between requested ad types and the player.

Mismatch in Linearity (Error 201):

• Cause: A non-linear ad returned when a linear ad was expected.
• Solution: Publishers and buyers should collaborate to ensure correct linearity is specified and adhered to.

Creative Duration Mismatch (Error 202):

• Cause: Discrepancy between the returned creative duration and the media file duration.
• Solution: Publishers and buyers should verify that creative duration aligns with the specified duration in the ad request.

Size Compatibility Issue (Error 203):

• Cause: Returned media files not compatible with the requesting device.
• Solution: Publishers should alert buyers, and buyers must return media files compatible with various devices and technologies.

General CompanionAds Error (Error 600):

• Cause: Inability to display a companion ad.
• Solution: Publishers should check for ad-serving issues and alert buyers to ensure valid creatives.

Companion Creative Dimension Discrepancy (Error 601):

• Cause: Companion ad size in VAST response not matching the display area.
• Solution: Publishers should ensure companion ad requests fit the ad unit dimensions, while buyers must return correct-size companion ads.

Inability to Display Required Companion (Error 602):

• Cause: Failure to display the companion ad included in the VAST response.
• Solution: Publishers should investigate ad serving problems and communicate with buyers to ensure the creative is valid and displayable.

Companion Resource Retrieval Issues (Error 603):

• Cause: Failure in delivering a valid creative for the companion ad.
• Solution: Publishers should notify buyers about any issues, and buyers should confirm that the creative is properly hosted and accessible.

Unsupported Companion Resource Type (Error 604):

• Cause: Requesting an unsupported creative type for the companion ad slot.
• Solution: Publishers should request only supported creative types, and buyers should respond with compatible creatives.

Undefined VAST 2 Error (Error 900):

• Cause: Encountering a VAST 2 error despite specifying VAST 3 in the request.
• Solution: Publishers may switch to requesting VAST 3 or ensure their network defaults to VAST 3, while buyers should troubleshoot and provide appropriate responses.

Best Practices to Prevent VAST Errors

To mitigate VAST errors and ensure smooth ad delivery, consider the following best practices:

• Pre-emptive Measures: Demand-side platforms (DSPs) should thoroughly review all creatives before serving. This proactive approach can prevent potential issues and ensure that ads meet industry standards.
• Collaboration with Partners: Working closely with supply-side platforms (SSPs), DSPs, ad networks, and ad servers can enhance the performance of VAST creatives. Alternatively, partnering with a monetization platform like Snigel can streamline this process.
• Optimizing Media Files: Implement media files with various bitrates to allow the video player to select the best option based on network speed. This optimizes the viewing experience and reduces playback issues.

Common Scenarios Leading to VAST Errors

Understanding the typical scenarios that lead to VAST errors can help in proactively addressing them. Common triggers include:

• Incorrect Tag Implementation: Mistakes in implementing VAST tags can lead to various errors. Ensuring that tags are correctly implemented and conform to IAB standards is crucial.
• Player and Ad Compatibility Issues: Incompatibility between video players and ad types or formats can result in errors. Regular testing across different players and formats helps identify and rectify these issues.
• Network and Connectivity Problems: Connectivity issues can disrupt ad delivery, leading to timeouts or incomplete ad responses. Optimizing ad delivery for varying network conditions can mitigate these problems.
• Creative-related Issues: Problems with the ad creative, such as incorrect formatting or unsupported file types, often cause errors. Ensuring creatives are properly formatted and compatible with various platforms is essential.

Additional Best Practices for Publishers and Advertisers

Publishers and advertisers can adopt several strategies to minimize VAST errors:

• Regular Monitoring and Testing: Continuous monitoring of ad delivery and regular testing across different environments can help identify potential issues early on.
• Clear Communication Channels: Establishing effective communication between publishers, advertisers, and technology providers ensures quick resolution of issues as they arise.
• Staying Updated with Standards: Keeping abreast of the latest IAB standards and updates in VAST specifications helps in maintaining compliance and reducing errors.
• Utilizing Advanced Tools and Platforms: Leveraging advanced ad serving tools and platforms that provide detailed insights and error reporting can significantly aid in troubleshooting VAST errors.

Key Takeaways

VAST errors can be a significant hindrance in digital video advertising, impacting user experience, ad engagement, and revenue generation. Understanding the types of VAST errors, their causes, and solutions is crucial for anyone in the digital advertising ecosystem. By following best practices and maintaining open communication between all parties involved in the ad delivery process, the impact of these errors can be significantly reduced.

Publishers and advertisers should focus on accurate VAST tag implementation, ensuring compatibility between ads and players, and addressing any creative or connectivity issues promptly. Adopting a proactive approach to monitoring and testing, staying updated with industry standards, and utilizing advanced ad serving technologies are key to minimizing VAST errors and optimizing digital video ad campaigns.