Lesson 6 of 7
A Field Guide To Common Bugs
Most tracking bugs are one of a small set. Recognise the symptom and you know where to look.
Tag didn't fire
- Trigger condition didn't match, check a variable's value.
- Trigger fires before the dataLayer push (timing).
- A blocking/exception trigger caught it.
Tag fired, data wrong
- Number sent as a string (ep.value vs epn.value).
- Variable resolved undefined / empty.
- Wrong dataLayer key or dot-path typo.
More usual suspects
- Double-firing: two triggers, or a tag without "fire once", look for duplicate
collectrequests. - Timing: the tag reads a DOM value before it renders, or fires on Page View instead of the custom event.
- Consent: tags held because consent is denied, expected behavior, not a bug.
- Cross-domain: the
_glparameter missing on the link, so the session splits.
Key takeaway
Sort the symptom first: didn't fire (trigger/variable), fired-but-wrong (type/path), or fired-twice (dedup/timing). Each points at a specific layer to inspect.