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ChatGPT's Missing UTM Tag Was a Bug, Fixed on 15 October

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Cartoon of a round sage-green character in a white plaited headband holding up a luggage tag lettered UTM, looking on in surprise as a small purple beetle snips the tag's string with scissors.
A ChatGPT bug stripped the UTM tag from many of its links between 8 and 15 October. Illustration: AI-generated.

From 8 October 2026, many links clicked in ChatGPT answers reached sites without the utm_source=chatgpt.com tag. Visits that arrived with neither the tag nor a referrer were counted by analytics tools as Direct. Cedric Huesler of Adobe, who tracked the drop across thousands of domains in Adobe’s analytics data, reports that OpenAI told him on 14 October it was a known bug. The fix began rolling out early on 15 October, Pacific time, and by that morning tagged ChatGPT clicks were back to 95 to 100% of the same hour a week earlier.

The loss was partial and uneven. In Huesler’s data, ChatGPT visits that could be attributed fell to about a third of normal within hours of the tag disappearing. Profound, which sells AI-visibility tracking, found that the share of collected ChatGPT answers with at least one tagged link fell from about 98% on 8 October to 66% on 14 October, and linked the missing tags to the rollout of ChatGPT’s new Intelligent UI answer format. Some links reached by opening a panel inside those same answers kept the tag.

Annotate 8 to 15 October in GA4, Adobe Analytics or any dashboard that reports ChatGPT as a source. Inside that window ChatGPT-attributed visits are undercounted and Direct is inflated by the same visits, so a dip in one and a rise in the other on the same landing pages is the bug rather than a change in demand. ChatGPT visits are still best identified by the UTM tag rather than the referrer: many ChatGPT links reach sites with no referrer at all, so the tag is often the only thing naming ChatGPT as the source.

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