Apple shuts The Trade Desk out of iPhone browsers until iOS 27.2

The block and what it stopped

Apple released iOS 27 on 14 September 2026, and Safari came with it carrying a new enforcement mechanism called IS_REQUEST_UNCONDITIONALLY_BLOCKABLE, a network-level block list that stops requests to named domains before they can complete, with no cookie or tracking variable to strip.^[1] Intelligent Tracking Prevention (ITP), which launched in 2017, removed cookies and partitioned storage but let the request go through. IS_REQUEST_UNCONDITIONALLY_BLOCKABLE kills the request outright.

Eight domains landed on that list at launch: adsrvr.org, uidapi.com, id5-sync.com, eu-1-id5-sync.com, rlcdn.com, pippio.com, permutive.com and ad.gt.^[1] Those domains belong to The Trade Desk, Unified ID 2.0 (UID2), ID5, LiveRamp, Permutive and Audigent, covering both ad delivery and post-cookie identity vendors in a single update.

Ian Meyers, Senior Director of Engineering at The Trade Desk, filed in WebKit Bugzilla on 21 September. Meyers said in the bug thread that adsrvr.org is The Trade Desk's core ad request and delivery domain, not an identity domain.^[1] adsrvr.org does not store user profiles or link identifiers; it serves the ad. Blocking it stops The Trade Desk's ads loading in affected browsers.

The bug thread and Apple's response

WebKit Bugzilla bug 324771 is the only public record of any communication between Apple and The Trade Desk on the matter. Apple made no announcement when iOS 27 released and issued no guidance to buyers or agencies.^[2]

John Wilander, Apple's Manager of WebKit Privacy and Adtech, responded in the thread on 5 October 2026. Wilander said he would notify The Trade Desk if and when any changes were available for testing, before confirming a new iOS 27.2 beta at build 24B5099f and asking The Trade Desk to test it.^[1] Apple has not set a public release date for iOS 27.2.

The gap between the iOS 27 launch on 14 September and the 5 October beta confirmation means The Trade Desk's ad delivery ran blocked on Safari for at least three weeks before a fix entered testing. Buyers who did not check campaign delivery against device-type breakdowns during that period had no official prompt from Apple to do so.

The doubleclick.net question

Google's ad.doubleclick.net, the domain that routes a large share of open programmatic inventory, does not appear on the block list.^[3] Apple has given no public explanation for its absence.

AdExchanger reported that hundreds of ad tech firms may ultimately be added to the block list.^[4] Which domains get added next, and on what criteria, remains Apple's call, with no said process or appeal mechanism for affected vendors.

Scale: which devices carry the block

iOS 27 runs on iPhone 11 and later and on iPad Pro, iPad Air, iPad and iPad mini models from their fourth, fourth, ninth and sixth generations respectively, a device eligibility list that covers the substantial majority of iPhones and iPads in active use globally.^[5]

Outside the EU, Apple's App Store rules require every browser on iOS to use the WebKit framework, so in Australia the block list applies to Chrome, Firefox and all other iOS browsers, not just Safari.^[6] A Trade Desk campaign targeting iOS devices has no browser-level workaround while adsrvr.org remains on the list.

What Australian buyers should check now

Any campaign running through The Trade Desk, or using UID2 or LiveRamp as an identity layer, should be pulled against a device-and-browser breakdown for the period from 14 September to the date iOS 27.2 releases publicly. Safari on iOS devices will show a drop in impressions, clicks and any conversion event that requires an ad request to resolve via adsrvr.org, uidapi.com, rlcdn.com or pippio.com.^[1]

John Wilander confirmed testing began with build 24B5099f on 5 October 2026, and Apple has not said when that build reaches the public release channel.^[1]