Google Ads client-side issue

Impact on Google Ads client-side tracking

Issue is that response on the request a ‘text-plain’ is and therefore the image fails to load, which is a false error.

 The root cause of the problem lies in the request to https://www.googleadservices.com/ccm/conversion/<Conversion ID> made by the Google Ads conversion tag in GTM when triggered. This request uses an image load method in the browser. However, the response returned by Google's servers is "text/plain" and empty, leading the browser to believe the image load has failed.

https://www.googleadservices.com/pagead/conversion/879937580/?random=1746524568219&cv=11&fst=1746524568219&bg=ffffff&guid=ON&async=1&gcl_ctr=1&gtm=45be5521v9168248762z8849587338za201zb849587338&gcs=G111&gcd=13r3rPr2r5l1&dma_cps=syphamo&dma=1&tag_exp=101509156~103101750~103101752~103116026~103200004~103231718~103231720~103233424~103251618~103251620~103252644~103252646&ptag_exp=101509156~103101750~103101752~103116025~103200001~103231718~103231720~103233424~103251618~103251620~103252644~103252646&u_w=2560&u_h=1440&url=https%3A%2F%2Fwww.bloompost.nl%2Fview-gifts&ref=https%3A%2F%2Ftagassistant.google.com%2F&label=2NYrCObQlfMYEKyQy6MD&hn=www.googleadservices.com&_dbg=1&frm=0&tiba=Zen%20Again%20%7C%20Cadeauset%20met%20amberblokje%20%7C%20BloomPost&value=0&currency_code=EUR&did=dMWZhNz&gdid=dMWZhNz&edid=dMWZhNz&bttype=purchase&npa=0&us_privacy=1---&pscdl=noapi&auid=1604418308.1746524318&uaa=x86&uab=64&uafvl=Chromium%3B136.0.7103.48%7CGoogle%2520Chrome%3B136.0.7103.48%7CNot.A%252FBrand%3B99.0.0.0&uamb=0&uam=&uap=Windows&uapv=19.0.0&uaw=0&fledge=1&capi=1&_tu=Cg&data=ads_data_redaction%3Dfalse&rfmt=3&fmt=4

_gcl_au 1.1.999770491.1739173633

_gcl_au 1.1.1604418308.1746524318

This request https://www.googleadservices.com/ccm/conversion/<Conversion ID> is made only under certain conditions and is directly tied to the values stored in the "_gcl_au" cookie.

1.1.1604418308.1746524318

1.1.2051094682.1746525583

2051094682.1746525583

This cookie can be created in several ways:

• By the Conversion Linker tag in GTM
• By the Google Tag either implemented via GTM or directly on the page
• By the User-provided data event tag in GTM (a separate event on a page containing personal data prior to conversion)

However, the "_gcl_au" cookie can be modified to have a longer-than-usual value, containing more information.

Why you might see “Firing Status Failed” in GTM Preview — even when it works

If you've ever tested a Google Ads conversion tag using Google Tag Manager Preview and saw a "Failed" status, you're not alone — and it's often not a real issue.

Here’s what’s actually happening behind the scenes:

When a Google Ads conversion tag fires, it typically sends a request using an image pixel (<img>) to a URL like:

https://lnkd.in/dBDnPD74

Google receives this request and processes it correctly, but responds with a text/plain response instead of returning an actual image (image/gif). This causes the browser to think the image failed to load.

Since the GTM Preview relies on the browser’s feedback, it interprets this as a "Failed" tag — even though the request was sent and tracked successfully.

So, the status you see in Tag Assistant is a false negative. It’s just a technical quirk of how image-based tracking and browser behavior interact.

If you're seeing this, don't panic. You can confirm the tag's success by checking:

• Network requests in DevTools

• Google Ads conversion logs

• Tag diagnostics in Google Ads or via enhanced conversion setups

This is a common point of confusion, especially when debugging new setups — so I hope this saves someone else from going down the rabbit hole.