iOS 27 Safari blocks The Trade Desk ads. Google bids still go through

The iOS 27 Safari browser stopped loading adsrvr.org, the domain The Trade Desk uses to deliver ads. AdExchanger reported it on 29 September 2026. Apple shipped the system on 14 September, so the fault sat in the open for more than two weeks.

Apple shipped iOS 27 on 14 September and adsrvr.org went dark

Buyers noticed within a week of the release. Safari would not resolve the address. When a domain does not resolve, the browser never asks for the ad. Nothing at the identity layer can work around that. The ad simply does not appear.

ID5, LiveRamp, Audigent and Permutive sit on the same list

The block also covers UIDAPI.com. That address serves Unified ID 2.0, the log-in based identifier The Trade Desk built with other firms. Four more companies are affected: ID5, Audigent, LiveRamp and Permutive. Google kept serving through ad.doubleclick.net in the same period. In tests described by AdExchanger, Google bids went through and The Trade Desk bids did not.

Ian Meyer says adsrvr.org carries ads, not identity

Ian Meyer, senior director of engineering at The Trade Desk, called it the “core ad request and delivery domain, not identity”, in comments quoted by AdExchanger. The difference matters. Safari has blocked third-party cookies for years. This time the browser blocked the pipe that carries the ad itself. The company cut 15 per cent of its staff earlier this year, so the timing is poor.

John Wilander has not said whether Apple will change the list

John Wilander, who works on privacy in WebKit, said he would report back “if and when any changes are available” for testing. Nothing had changed by 29 September. Neither firm has said whether the block is a bug or a decision. The Trade Desk has spent the year pushing into new screens, including home screen ads on Telly sets.

Pull your Safari delivery numbers for the second half of September and set them against August. If the list stays as it is, a campaign bought through The Trade Desk will not reach an iPhone that has updated.