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

Update (28 Oct 2020)

Well my errors came back, The good folks at UniConsent investigated and found out that I was caching, information (Javascript,) that was being called, and so breaking the TCF rules again. I logged a call to the people who provide my WordPress Caching Plugin (WP-Rocket.) Who remoted onto the server, and added the following onto their ‘File optimisation’ Settings;

Exclude inline Java WP-Rocket

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!

Which Ad Network Should You Replace Adsense With?

For everyone asking “What ad network did you move to”, then you can message me (link above) and I will let you know. There are some caveats, most of your traffic needs to be EN-US / EN-GB traffic, and you need to have a decent amount of traffic to be considered. If you fall into that category, message me and I will pass on you details to them. (Disclaimer: I get a financial kick back for doing so). 

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Author: PeteLong

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    • Yes problem is ongoing, my site Cache plugin is now breaking things, this page will get updated when the problem is finally fixed. It takes me about an hour a day working on this problem and its still not resolved!!! (26th Oct 2020)

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  1. Is this still ongoing?

    I had the same thing on adsense appear. 8 days later still there though when I click to view report shown is one from 8 days ago.

    I’m using same plugin (Uniconsent) nut not WPRocket.

    One other thing is that now site visitors on adsense are far below levels seen in Ananytics and WordPress stats

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    • Hi JP, Problem is now resolved.

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      • How did you resolve it Petelong ? I have two errors 1.2 and 1.1
        No idea how to fix it..I’m using W3T cache and cdn
        Please can you help ?

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        • I repeatedly kept going back to UniConsent and they told me what was broken, I fixed it, waited a bit longer, and repeated the process until the errors went away. All was well for a few weeks, and it started again, I lost my temper with Google and removed ALL Google ads and replaced them with another ad provider, who pay me more money and give me no hassle win/win.

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          • Who were the better ad providers? As I am done with Google. To many rules.

          • If you contact me (link above) I will let you know.

  2. Which ad network pays better than Adsense??? saw your post

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    • See updated comments above….

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  3. Well, the problem appeared in my account a month ago. I did some changes and the message was gone, until today which appeared again. This is driving me crazy, Google should have found a better way to make the whole problem more automatic and easy for newbies. This is a situation mostly for developers, not simple users who try to run their blogs by just writing new content.

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    • It forced me away from Adsense, I’ve only just gone back – Since I have the error has not re-appeared.


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