Data tag sometimes don't sends events to the server

Google Tag Manager Server Container
1

Hello there! I really enjoying to use the Data tag and the Response tag, I use the server response custom events in the web triggering some Fb and Google tags, because of the lack of my webshop engine and consent mode.

When I testing in the debug, everything looks correct, responses cames back, tags triggering in most of the cases. But sometimes I see the data tag still “running”, or succeded, but sending no event to the server. Mostly the problem happens with the purchase event. I tested the data tag triggering on lesser events, and sending lesser parameters and no user_data, but the problem still here.

I don’t think it is a debug problem, when I use the custom server response purchase event triggering the conversion tags some conversions are missing.

I use one data tag for pageviews and one for the other events. Maybe using two of these are the problem? I use the DC client. And the problem is there with cosent granted too.

Sometimes I see in the devtools that application - cookies has an alert in chrome: “Cookies from https://mywebshop.hu may have been blocked due to third-party cookie phaseout.” It could be the problem? I send the fbc and fbp parameters with the data tags and stored in cookies, I tested the tag without these, but this message still popped out.

Do you have some advice for me?

2

Hi,

It seems the issue may be linked to the page redirecting to the Thank You Page too quickly after a purchase, meaning the tag didn’t have time to complete its request to the server
The first thing to try is to go to the Data Tag settings and tick the box next to ‘Use fetch instead of XMLHttpRequest’. This will allow the tag to fire without waiting for a response.

Screenshot 2026-04-02 at 11.52.37
Screenshot 2026-04-02 at 11.52.372300×1240 155 KB

The next option is to move the purchase event to the Thank You Page if the redirect to it happens very quickly.

I use one data tag for pageviews and one for the other events. Maybe using two of these are the problem?

Regarding your current setup, I recommend creating a separate tag for each event with it’s own trigger, as this is best practice and different events require different payloads, giving you more control over the payload for each event.