ADVISORY: Spike in 400 VAST Errors in IMA SDK as of July 15, 2020

Advisory for Video Ad Operations Teams

Watching That has recently detected a spike in the number of ad errors coded as VAST 400 across our network of customers that use the IMA SDK.

Example of spike in 400 VAST Errors on Android / Chrome


Starting on July 15th, 2020 the number of errors recorded by the platform and coded as a VAST 400 error grew significantly on Android / Chrome inventory.

At the time of publishing this post the error volume remains HIGH and the severity level is HIGH.


The likely cause is the creative being loaded contains a video file in a format that is not supported by the Android operating system.   For example the file is formatted using the .m3u8 (HLS) codec which is not supported by Android / Chrome.

This also looks to have coincided with the release of Android Chrome v84 and ad ops teams should consider that this issue might continue to grow in size and impact as more devices upgrade.

Recommended Action

Remedial steps include:

  • Ensuring all creatives are formatted and targeted in way to ensure compatibility with the device and operating system.  In programmatic setups ensure all partners are aware of this issue.
  • Leverage the IMA SDK mimeType property to control which file format is selected.



This error has been seen across a multitude of accounts and setups that use the IMA HTML5 SDK on Android/Chrome devices.  And example is shown below.

Another example of the 400 VAST Error spike seen on Chrome / Android


If you have any questions please get in touch.



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