Purchase Event missing some Deduplication Parameters for FB Pixel

13 0 9

I've integrated my FB pixel through Shopify and haven't done any manual edits. I use 'maximum' for customer data sharing options, which I know uses the conversion API. However, I don't know why it still runs into a deduplication error (I've also noticed this during my campaigns). To fix it, FB recommends:

"Add an event_id parameter to all Purchase events that you're sending from both your pixel and the Conversions API. To add an event_id parameter to the events you're sending through the Conversions API, you can use the Payload Helper tool on the Facebook for Developers site to validate that your payload is set up correctly. To add an event_id parameter to the events you're sending through your pixel, go into your website's source code and add an event_id parameter to each of your Purchase event instances."

I'm not technical enough to do this. Is there another way I can keep the maximum customer data sharing option and fix this issue? Or can I find someone able to do this?


Replies 55 (55)
3 0 1

Would you mind sharing the code with us, please? 

New Member
2 0 1

Yes, we do.

PM me if interested.

11 0 3

Hi Rosemary,

Here's a brief-ish overview for using Google Tag Manager to collect conversion data in Shopify and then forward it onto any number of endpoints, including Facebook Pixel, Facebook CAPI, Universal Analytics, and Google Analytics 4.


Let me know if you have any questions.


11 0 3

Hi there,

Yes, we do offer a service for doing this.

For watch this video:

Then let me know if you have any questions.


10 0 3

Heya mate...fellow kiwi


I am forver getting these warnings http://prntscr.com/1x1hnzl always got this issue http://prntscr.com/1x1htcu tried many times connecting pixel a few different ways but still like this http://prntscr.com/1x1hus1 ...do you think this is effecting sales?....I am using a Lookalike AUDIENCE that has 1 years data but sales since this IOS issue have been going from bad to worse, I am now at 10% sales of what I was at 6 months ago, and tbh my roas is just about to the point it is not worth continuing which is a shame because the products sell like hotcakes when the right audience is being targeted in my FB ads.......do you think setting it up correctly like you have in the video using Tag etc would increase sales?....if so what is your cost to set it up?

11 0 3

Hello fellow Kiwi!

Yeah you're getting the deduplication error.

Essentially, for whatever reason, a small portion of shop owners like yourself are having issues with the native Facebook app. It's supposed to send an identical event_id on both the pixel and the server side event. But it's not doing that. Instead, the pixel sends a different event_id from the server for the exact same event. Hence, why you're getting the error.

You're facing two separate but related issues...

1. Attribution

2. Reporting

Attribution affects the way FB ads auto-optimizes your ads.

Reporting affects your knowledge about whether an ad, adset, campaign, or channel is profitable or not. So you could be scaling unprofitable ads up and scaling profitable ads down. I suspect this is an issue you're facing with shrinking ROAS.

The first place to start is collecting reliable first-party data - that is, data you own and control yourself. Then you can forward that data onto any other endpoint you want... FB ads, Google ads, Universal analytics, Google Analytics 4, Pinterest, Tik Tok etc.

Once you have clean reliable data, there is so much more you can do. But this first step is critical to get right, because if you're working with unreliable data, nothing you do after that will help. 

Setting up correct reporting is the next step. Relying on Facebook stats is nonsense. Google analytics setup properly is a much better place to organise things. But there are MUCH better options than Google Analytics for reporting. We pipe data to bigQuery then build dashboards in Data Studio.

There are also other excellent reporting tools that we are partners for that we can recommend (and get you a cheaper deal). The best 3rd party one I can recommend is WickedReports. It's really an amazing reporting tool. Not beginner-friendly. But once you understand that data can tell you different stories, depending on how you query it, you'll quickly learn the value of WR.

Regardless of whether you choose to use WR or not, you should be collecting your data in a single-source-of-truth repository that YOU control and own. bigQuery has my 100% recommendation for this job. And the running cost is quite small (maybe a few dollars per month, quite amazing for the querying and machine learning capabilities you're unlocking). 

In terms of the way your advertising, you'll probably need to change your approach... especially with how iOS changes are messing with everything.

95% of your success with sustained long-term ads is in 'the creative'. Meaning, precise-interests etc are almost a complete waste of time now and are probably harming your ROAS significantly. Go as broad as humanly possible with your targeting. Do A LOT more ideation with your image, headline, text, link text, CTA. Studies show top few % of earners with ads are split test something like 15x more creatives. BIG time media buyers have known this for several years now. The smaller advertisers have no idea about this and have been fretting over sophisticated targeting rules that virtually guarantees their ads will burn out quickly.

Hope that helps.

Oh in terms of costs... schedule a call and let's go through it.