Google Ad Manager Advanced Troubleshooting Guide for Display Ads

DoubleClick For Publishers / Google Ad Manager Ad Optimization
March 20, 2023 | by Aleesha Jacob

Troubleshooting ad serving and delivery should not be a daunting task. When something breaks, there has to be something that tells you exactly what is going on and how to fix it. In fact, a good tool not only tells you when something goes wrong but warns you beforehand.

Below we provide you with a guide on how to diagnose ad-serving issues and the best tools to use:

Loading Chrome Developer Tools

While the webpage you are troubleshooting is open, you can load devtools by a keyboard shortcut CTRL+Shift+C or simply hitting the F12 key.


The Elements tab opens if using CTRL+Shift+C.


F12 key opens the Console tab.

Exporting a HAR file

HAR (HTTP Archive) is a file in JSON object format with a particular field distribution, used by several HTTP session tools to export the captured data (source: There will be times when Google support would ask for this file to assist them in troubleshooting.

Be careful with this file as it contains sensitive information:

  • Content of the pages downloaded while recording
  • Any information submitted while recording, like personal details, credit card numbers, passwords
  • Anyone with your HAR file can impersonate your account because it also contains your cookies

If Google publisher support asks for a HAR file, here’s how to export it:

Step 1: Open DevTools

Step 2: Go to the Network tab

Step 3: Right-click on any of the contents

Step 4: Save all as HAR with content

har file

Step 5: Select a folder

Step 6: Save

How to Check Google Ad Manager Ad Requests

GAM ad request

Search for ads? in the Network tab. Ad request calls are those that start with in the request URL. Important values to check are the following:

  • iu_parts – the GAM network ID and the ad unit where the ad request came from
  • prev_iu_szs – the ad unit size/s requested
  • prev_scp – custom parameter or targeting criteria
  • URL – the URL that buyers see in the bid request

How to Check Google Ad Manager Impression Pings

GAM impression pings

Filter or search for view? in the Network tab. This allows you to verify if impressions are firing and accounted for.

How to Check Google Ad Manager Viewability (Active View) Pings

Google ad manager active view pings

Search for activeview? in the Network tab. Important values to check are the following:

  • p – position or pixel coordinates of the creative displayed and is in order: top, left, bottom, right. If you see negative values, that means it’s outside the viewport and probably not viewable.
  • mtos – time the creative was on screen in milliseconds.
  • bs – browser size; pixel dimension of the viewport. A negative value means the ad was probably not measurable.

You can find more information here.

How to Check Google Ad Manager ad clicks

Source: Google

Search for click? in the Network tab. This is to check if clicks are firing and if multiple click pings are being fired which could lead to discrepancies or inaccurate reporting. Important values to check:

  • xai – click tag purposes
  • adurl – the landing page when user clicked the ad

Using GPT Publisher Console

The Publisher Console is a handy tool from Google that allows you to understand webpages’ ad requests, winning line items, and underlying tagging mechanisms.

The simplest way to activate it is by appending the URL with ?google_console=1. You may also type in javascript: googletag.openConsole() on DevTools’ Console tab.

using Google publisher console

Once activated, use Ctrl+F10 (Windows) and Fn+CTRL+F10 (Mac) to open/close the Console.

Ad Slots tab provides information about the ads, line items, and creatives served on-page.

ad slots

Page Request tab helps you understand page requests and their mechanisms.

page request tab

Using PubGuru Ad Inspector

PubGuru Ad Inspector is a Chrome extension with more sophisticated checks and features, making it the troubleshooting tool of choice for publishers. It can run on any device regardless of the screen size. It can diagnose issues with Header Bidding and Google Ad Manager providing clear actionable advice on errors, warnings, and passes.

Download it from here.

pubguru ad inspector

PubGuru Ad Inspector has different tabs performing different levels of checks so you see everything that’s going on with the site in real-time and take action as needed.

When you sign up with PubGuru, you’ll get Smart Notifications, which means you get notified in real-time when something goes wrong saving you time from having to manually check the site every so often.

pubguru notifications

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