Adsense: ‘We’ve detected an error on your IAB TC string’

KB ID 0001709


A couple of weeks ago I logged into Adsense and saw this;

Adsense Issue on your IAV TC String

‘We’ve detected an error on your IAB TC string on one or more of your sites or apps. These errors may affect your ability to serve ads to European users. A detailed report is available for you on the EU user consent page’.


Well all of that made no sense to me, so I downloaded the report, which is a spreadsheet and it looked like this;

Adsense TCF Error Report

Erm OK, so what’s error 2.1a? well it’s this;

Erro 2.1a TCF

Everything I read didn’t make much sense, and a search of Google revealed a ton of things that made little or no sense to me.

Why Am I Seeing European IAM TC String Errors?

In short: People in Europe are protected by the GDPR. This says, (very basically) that website visitors should be ‘asked’ what their Ad preference, and tracking cookie preferences are, BEFORE the website can show them any ads, or attempt to embed tracking cookies, (like the ones Google uses), on their machines.

This is why you will notice most sites you go to now ask you about cookies and ads the fist time you visit,  you generally then tick a box that says ‘accept preferences‘, or ‘that’s fine‘, and you are bothered no more.

So that’s basically the root cause of the problem. Well I run my website on WordPress so “There will be a plugin for that right?” I tried a few and settled on UniConsent CMP. I installed it, and enabled cover for GDPR, (and CCPA compliance).

Note: Sign up for a free licence, then you can manage everything directly at UniConsent.

Extra Tip: Go To Consent Manager Version 2 > Manage > Fill everything in  > Enable GDPR (For European Countries) > Enable IAB TCF > Select Pop-up Box > Save and Exit (Top right).

Do You Cache Your Website? If so, don’t forget to ‘flush the caches’ at this point.

So That Fixed It Yes?

Sadly no, but because I now manage my CMP online they have a support/chat feature, and I was asked to do the following;

    1. A third party Ad agency I use has their own CMP I asked them to disable that, which they did, (don’t forget flush the caches again!)
    2. I had some embedded code with my Adsense ads that was calling this script;
script async src="//

I had to remove each instance of that, and put the following code in my websites < HEAD > section; Download Code

The Adsense TCF Error Wont Go Away!

That’s because the errors stay on Google Adsense for 7 DAYS, even if you have fixed the errors, you need to wait 7 days for the errors to stop showing!

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Author: PeteLong

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