0% deduplication events error

Hello everyone.
Yesterday (22.10.2021) all of my clients received a deduplication error, all events.

To deduplicate identical events received by both your pixel and the Conversions API, we need to identify them by cross-checking a matching deduplication key in both sources.

Some of your Purchase events don’t have a deduplication key, so we’re unable to cross-check whether they’re duplicate events. This means they’re potentially being incorrectly counted twice and leading to inaccurate ad attribution.

When you run debugging, you can see that the deduplication is working

But If open the deduplication tab, there is 0% for the server. I don’t understand why this is the case, before it was 100%, but now it’s 0%

Colleagues, tell me why facebook is writing error of deduplication, although it works, it can be seen in the picture above ?

Have you faced the same problem?
Maybe facebook changed the parameters of deduplication?

We use data client, data tag, facebook tag. All tags have been updated to the latest version.

Thanks, I’ll be glad to get any information about it


Looks like your local Facebook bug.
I had the opposite situation a couple of days ago. In debug mode the events didn’t deduplicate, but in fact they did, it eventually went away on its own within 24 hours.
Try marking all issues as resolved and see if the problem resumes.

@Alex Hi,
The thing is that not only I see it, but all clients observe these errors.
Thanks, I’ll try marking them as resolved and see if they appear again.

How do you send the event Id to the server? (In what field?)
Are you sure that the unique event id is generated correctly?

Can you share a link of the site?

hello @Denis .

I send event_id from web container like this

Yes, I’m sure the unique identifier is correctly generated. We use your template and supplement it with fbp. When tested through a pixel, the deduplication works.
Everything was working until 22.10.2021


Checked. I don’t see any issues with your setup. Look like really some bug in FB. Did you try to change pixel ID or write to FB support?

Thank you.

Did you try to change pixel

Do you mean create a new pixel for this account ?

write to FB support

No, not yet

Yes. Try to create it in other business manager.

Okay, I’ll give it a try.
@Denis thank you very much for your time.

I saw that issue is resolved. Deduplication event_id 0% · Issue #25 · facebookincubator/ConversionsAPI-Tag-for-GoogleTagManager · GitHub

My congratulations! :slight_smile:

@Denis, hello.
That’s not exactly true :slight_smile:
I’m sorry, maybe I didn’t express myself correctly.
I meant that in the event manager I just clicked the “Mark as Resolved” button.

I am facing exactly the same problem.

Differently than @111 I am sending the event_id from Web Container like this (as a Custom dimension)

and from the Server Container like this

@Denis do you see anything wrong?

From your screens look like everything is configured correctly.

I don’t have this issue that’s why I can’t test approaches to find a workaround on it. However, I saw a few similar issues to this one across the internet. And the only suggestion I have that’s trying to do the same on the new business manager with a new API key and new pixel.

As for me, this looks like a Facebook UI bug.

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Hi, congratulate me :slight_smile: .
I finally figured it out.
The problem was that the test_event_code value was passed with all events. I set test_event_code to undefined.

Now every event is sent without test_event_code.
That’s it, problem solved.

It should take 1-2 days for the status to be updated

But there were no problems with test_event_code before, maybe facebook changed something.

hi @Francesco_C, check, you may have the same problem

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My congratulations. Thanks for this message.

Here is an approach that I use by myself for FB Test ID (we should create post about this):

@Denis, hi.
Cool done, i’ll try that too, thanks for that.