Fix Firing Status “Failed” - Google Tag Manager & Google Ads

This week while doing Acuity Scheduling offline conversion tracking for Google Ads, I’ve been struggling with a super annoying problem.

First conversions go through. Next ones fail.

Tested different GTM. Different ad account. Different website.

Looking for answers

The conversion tracking GOAT Simo Ahava had a blog post on failed GTM tags, but unfortunately, those solutions were not relevant here.

Tests

I ran a bunch of tests first without finding the issue.

• ✅ Not related to consent mode settings or overrides

• ✅ Not related to Google Ads conversions being set to “once” instead of “every” which would have been the most logical as that’s exactly what’s happening here

• ✅ Not related to ad blockers or browser profiles

• ✅ Not due to Google Ads conversions enhanced conversion user data

• ✅ Not caused by iframe implementation

• ✅ Tested on multiple Squarespace sites - issue persists

• ✅ Tested with fresh Google Tag Manager container - problem continues

• ✅ Tested with different Google Ads conversion IDs - same result

• ✅ Issue appears to be related to GTM/Google Ads interaction specifically

Solutions

If firing status in Google Tag Manager says “failed”, this may be due to Google Tag Manager user-provided data event which is used for Google Ad’s “Enhanced Conversions For Leads”.

I’m not sure why Failed tags happens with enhanced conversions for leads. It’s probably a bug in Google’s side. But nice to finally know what causes it.

🔑 Key ideas

1. First Google Ads conversions go through

2. After GTM user-provided data event all Google Ads conversions say “failed”

3. Even a new GTM, another website, another Google Ads account does not fix it.

4. Removing GTM user-provided data event does not help.

5. Clearing cookies fixes the issue. So we could dig which cookie it is but not sure if it helps.

I believe the tags do work and it’s a bug in GTM.
But not yet 100% sure. It also seems like it first said Fired, then turned into Failed, although I wasn’t able to replicate it as it’s so fast. Would need to record a video.