Inspect YouTube ad delivery

Ad Manager delivery tools help you troubleshoot ads

The YouTube ads inspector is used to see which partner-sold ads are eligible to deliver to your YouTube-hosted video content. Inspecting eligible ads can help you troubleshoot or understand ad selection. You can inspect ads that appear in YouTube videos on desktops, laptops, or mobile devices (also referred as mobile web). The YouTube ads inspector can't be used to for ads that appear in mobile apps.

Some common questions that can be answered by the YouTube ads inspector are:

  • Which ads delivered to my YouTube videos?
  • Why these ads and not others?
  • Are my line items and creatives set up correctly?
  • Why is my line item behind schedule or not delivering at all?

Details can be shared with other users in your network to help collaborate and troubleshoot.

Get started

  1. Sign in to Google Ad Manager.
  2. Navigate to Delivery and then Delivery tools and then YouTube ads.
  3. Enter a YouTube video URL and select a line item to troubleshoot.
  4. Click Continue.

The YouTube video will open in a new window. Return to the Ad Manager window to see ad delivery information ad they're served. You can advance the video player progress to see delivery information for each ad break.

In Ad Manager delivery tools, information about each request and what ad delivered is displayed. Each row on the page represents an ad slot and request. Click a row to expand more details, then click Simulate Request to determine why a different ad delivered than the one you expected.

Information about requests

  • Div: Identifies where on the page the ad slot appears, such as "top".
  • Requested sizes: All sizes defined in the ad request.
  • Key values: All key-values defined in the ad request. Click see all to see the full list.

Information about what delivered

  • Demand channel: The method used to select the ad, such as "Open Bidding" or "Ad server". Learn more
  • Advertiser, order, line item, and creative, each with their associated IDs. To open each in Ad Manager, click their respective names .
  • Line item type
  • Creative size
  • Creative type

Potential VAST errors

The following VAST errors may have prevented ad delivery. The descriptions and possible resolutions shown are specific to YouTube ad delivery inspection.

VAST error code Description and possible resolution
200 Check if you've trafficked a non-skippable ad longer than the allowed maximum of 30 seconds. 
400 Check the following for compliance:
  • GDPR compliance
  • Third-party serving and/or tracking for child-sensitive content
  • Ad is possibly disallowed
401 Media file not found. This issue should only occur initially and should resolve automatically once the file can be retrieved.
402 Check for issues on the player side such as an improper setup of a redirect or possibly a timeout in playing the ad.
408 Check whether the clickthrough URL is HTTP only. All tracking events, impressions, and click-through URLs must be HTTPS only.
901 Check whether you've trafficked a VPAID ad. VPAID ads are not supported on YouTube. This error may also surface if the VAST contains a single VPAID media file in the list of media files.

See all other VAST errors and their descriptions.

Block an Ad Exchange/AdSense ad or report an issue

The Creative details tab appears only if you're enabled for the "Review and block Ad Exchange creatives" user role permission.

Block Ad Exchange or AdSense creatives, or report a potential issue with them, via the Creative details tab. Next to "Suggestion", you can:

  • Block ad: Prevent the creative from serving. The blocked ads appears in the "Blocked" tab of Creative review.
  • Report to policy: Submit a creative that may have policy issues for review. 

These options are available only for Ad Exchange or AdSense creatives, not other kinds.

Share details

You can share the details with users who have access to your network. This helps you collaborate with others to help determine a plan for troubleshooting your line items.

  1. Above the details on the Troubleshoot page, click Share this session.
  2. Click Copy URL. The URL is now copied to your clipboard and ready to be pasted.
  3. Send the URL to a user with access to your network to paste the URL into their browser.

Simulate ad requests

A simulation shows which line item would win if you were to request the ad slot again. If an unexpected line item wins the simulation, you can see why. Change targeting and tag information to try and get the desired line item to win the simulation.

When you click Simulate request, Ad Manager runs a simulation and provides the details outlined below. 

The "Simulate request" feature doesn't retain information on page or server state. Therefore, competitive exclusions, roadblocks, and frequency caps will not match the original request.

Original request

This section recreates how the ad request you selected on the Troubleshoot page actually delivered. It includes:

  • Ad request details: The request and targeting information for the winning line item.
  • Winning line item details: The delivery details for the winning line item.
  • View non-delivery reasons: Click this button to see reasons why other line items were selected to serve over this one in cases that this line item was eligible. Here are details of the possible non-delivery reasons.


Shows what would happen if you were to request this ad slot again. 

Ad request details

The request and targeting information for the simulation, which defaults to the current settings.

Winning line item

The delivery details for the line item that wins the simulation.

Search for the line item you were expecting to win

If an unexpected line item wins the simulation, you can search for the line item you thought would win and click Go. Details for the winning line item and the reasons for non-delivery of the line item you searched for are shown.

Learn more about causes for line item non-delivery

Rerun simulation

You can change the targeting and tag information under "Ad request details" and then click Rerun simulation to see if the winning line item changes. If you eventually find a simulation that provides the desired winning line item, you can go back and update the actual targeting and tag information.

Why is the simulated winning line item different from the original?

There are several possible reasons for this. Here are a few:

  • Every run request, whether actual or simulated, happens dynamically. As a result, several things can change from one request to the other, including run time, goals, new line items to compete against, and so forth.
  • The ad selection process can result in different line items serving to requests.
  • The simulation only considers one ad slot at a time. Therefore, if original winning line item is part of a request with multiple ad slots, like a roadblock, it won't win the simulation.
  • The line item reached a frequency cap.
  • The line item met its delivery goal.

Why did my line item not deliver 100%?

Ad Manager distributes impression delivery based on both the Deliver impressions setting for the line items and Ad Manager pacing rules that attempt to optimize delivery. Changes to pacing may affect traffic and delivery.

If your think your line item isn't delivering properly, try the line item delivery troubleshooter or learn more about delivery pacing.

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