Why is Google Tag Manager causing errors on my checkout page?

[juanpfc]

Hello everyone. We are trying to set up some web pixels using Google Tag Manager using the new "Customer Events" functionality of Shopify on a store already in the new checkout. However, we are getting an error only happening on the checkout page. As soon as the script is executed, it returns this: Uncaught DOMException: Blocked a frame with origin "null" from accessing a cross-origin frame. I'm attaching a screenshot of the error for full context.

Any idea of why this might be happening? If I remove the GTM script, everything works fine. So it must be something related to the external script. I'll appreciate any help, thanks in advance!

[lov2code]

I am having the same issue. Has anyone found a solution to this yet? I have attempted to move the GTM tag outside of the pixel section and it doesn't read the datalayers. Very frustrating.

[akashgarg]

I am facing same issue, did any found any solution?

Very frustrating. Please help 

[00coder]

Receiving the same error. I have seen in some non-Shopify forums that window.postMessage() may be a solution, but I am not sure if or how that can be implemented here. Is anyone able to assist?

[R-Daneel]

I'm having a similar issue. I followed these instructions to set up my tracking pixel using Customer Events:
https://help.shopify.com/en/manual/promoting-marketing/pixels/custom-pixels/gtm-tutorial

but when I try to preview in GTM, I see an error in the browser console and preview tells me it can't find the pixel. When I view source, I see the pixel code is there. I'm surprised we'd be shown an implementation that doesn't quite work.

Uncaught DOMException: Failed to set a named property 'debugBadgeApi' on 'Window': Blocked a frame with origin "null" from accessing a cross-origin frame.

[keligijus]

Hey, it seems that the article suggests using a Chrome extension https://help.shopify.com/en/manual/promoting-marketing/pixels/custom-pixels/gtm-tutorial#:~:text=Add... , rather than GTM preview tool. I've managed to confirm the correct datalayer info using the Legacy Chrome extension.

The error seems to be related to the preview tool itself.

[MosAli]

I spent so long trying to work out what was wrong with my implementation and it was this all along. 

[DEVIZ]

Nobody is in a hurry to fix the topic 🙂

[Growth_Society]

Same problem here. It seem to be a serious topic pleas Shopify Team give us an answer ! 

[a6589932]

Has anyone solved this problem

[DEVIZ]

It's a simple 😉 There is a forced CORS policy error. The reasons for this error can be varied, and here are the most common ones: No local server, Trying to access frames from different domains, CORS policy on the server. Everything is based on the correct configuration of the server. The cors rules respond correctly but I have to have exceptions for google they use the iframe solution.The best thing is that you probably don't have to use an iframe so you won't have any mistakes...