ATC and PUR problems | Facebook Pixel using tag template


I have some problems with FB pixel on web container.
(FB Capi looking normal, at least for now, but I will test it after I will solve pixel issues)

After talking with a FB rep, he told me that indeed there are some problems (on their side), but when I told him that i use GTM (so, a 3rd party) he said that he cannot help me and I should reach 3rd party support.

So, I am testing only pixel events.
As you can see there is a 2nd Add to cart event without Event_id param.

Here is my ATC tag.

What I have noticed.
If I pause FB Page view TAG and FB View Content TAG, only one Add to event is fired, the correct one, with Event_id.

If I unpause FB Page View TAG, the second ATC is showing up.

Even more curiously, when I pause FB Page View tag, but unpause FB View Content TAG, the second ATC event comes up again.

Here are FB Page View and View Content TAGS

Now, if I unpause FB Page Views and View Content TAGS, I can see this (using WASP chrome add-on)
One ATC event, the good one, with Event_id and contents

The second one, without params.

As you can see both are from web tag template. I am using Simo‘s template and as we all know, is not his anymore - Meta owns it but with no updates.

Also, as you can see, there are some greeen lines. For each ATC event, the green line goes to

Things that might help (or not)

If I use Test code to test both server and browser, there will be 3 events

  • 2 of them correct - one from browser and one from server, both with event_id and params, server event is deduplicated
  • 1 event with no event_id and no params

The same situation is with Purchase event. But I think the solution for PUR will be the same as for ATC.

I can provide more screenshots or info if necessarily.
Can anyone give me, please, some guidance for this issue?


Hi Alin,

First of all I would try to use custom HTML tags instead of using tag template, because yes, they haven’t been updated for a very long time and there are problems with them on some platforms. I don’t recall this happening on WP though.

I would also look at this setting in the Pixel just to be on the safe side

Hi, @Alex

Thanks for your reply.

I was considering to use cHTML tags for FB Pixel, but I saw that is not very easy to use tag sequencing with cHTML tags. (Am I wrong?)

From your answer should I conclude that for your clients you use cHTML for FB Pixel?


Hello, Dan,

Yep, all good there.

One more thing that I forgot to mention.

In Business Settings, there is a System User that have access to my pixels.
The second pixel was created recently to test if my problem still persists with another pixel.

And I noticed that this System User (Conversions API System User) had immediately access to the new pixel.
I remember that for the first pixel, more that a year ago, I used the official FB plugin for woocommerce to install pixel on my website. But when I started using GTM, I deleted this plugin.

And ss far as I know, this System User is needed for server.
I tried to remove access to pixels and noticed that events sent from server to FB were not sent.

So, this has nothing to do with web container, but maybe this info can lead to a solution.


Looks like ATC is entering in a loop :wink:

More detailed infos for those 2 ATC events (the good one and the bad one).

Headers for the bad ATC

Headers for the good ATC

Preview bad ATC

Preview good ATC

Response bad ATC

Response good ATC

Initiator bad ATC

Initiator good ATC

Timing bad ATC

Timing good ATC

Cookies are the same.

Does this help to know where to look next?
I am puzzled.

hey Alin,

You don’t need any sequencing to pull off the HTML route. In order to make it a clean test:

  1. pause your existing ATC fb tag
  2. Add the following with the same trigger (replace values with proper variables, or for test-sake remove them all together:

fbq('trackSingle', 'PIXEL_ID_HERE', 'AddToCart', {
  'contents': '{{dv - fb_contents}}',
  'content_type': '{{const - content_type}}',
  'currency': '{{const - currency}}',
  'value': {{dv - value}}
    eventID: '{{Unique Event ID}}'

  1. see if the issue persists

I think I found the problem.
Makes no sense for me, but for now, in Events Manager, all events are deduplicated, no more extra ATC and PUR events.

Reading this article I remembered that a while ago (at least one year ago) I connected G Optimize with GA4.
Even if Simo says is not good to unlink G Optimize, I did it to see what happens.

Now all events are firing correctly.

Does this make any sense to you, guys? @Dan @Alex


Thanks @Dan for your reply.

I will do the test, I have nothing to lose :wink:

But as I mentioned before, the ATC FB event is fired even if I pause the tag.
I will come back here with the results.

Also, in order for this test to be correct, I think I have to re-link G Optimize, right? Please see my latest comment.

Many thanks,

Hello again,

After turning the internet upside down trying to find more people with my problem I came to this.

and an update

Meta Pixel BUG Update: who was affected and what's next | Meta Pixel Bug UPDATE: what pixels were affected, and what to do with your pixel if you had this bug. | By PixelYourSite | Facebook -

So, my “solution“ with un-linking G Optimize was the most stupid thing that I ever said. :wink:
Looks like it was just a coincidence between the moment I came with the “solution“ and the moment FB managed to solve the problem.

There are still some issues (I will monitor a couple of days), but the numbers are more closely to the reality than before.

I hope this will help others with the same issue.