VAST error 402, aka Unable to download or timeout of Media File URI, is an error that can be caused by a problem fetching or playing the Media File, and could be any of the following (1) The load Video Timeout is set too low in the IMA SDK. The default is 8 seconds. (2) Low bandwidth or poor website implementation with competing requests that delay loading of the Media File. (3) A video auto-plays in a mobile environment, whereas it should be click-to-play (there are some exceptions). (4) Showing video ads in an auto-play environment (for example, a playlist), while the window is not in focus (either another tab is selected, or window is minimized). (5) For players that use the IMA SDK, video fallback may be helpful to avoid losing impressions. To fix the error, the publisher should increase the timeout limit of their player via the SDK and the buyer should ensure that any CDN-hosted creatives are returned within the specified media timeout.