The Maze: On November 4, Meta released a new version of the Marketing API, the connection that lets retailers and agencies create Facebook and Instagram ads through their own software. If that software leaves certain settings blank, Meta can now add products to some new ads or show ads on devices the advertiser did not choose. The two changes start with version 27 and follow different rollout schedules. A third change takes away an older way for software to update a store’s catalog.
Source: Meta Newsroom. Meta’s March 2026 Product Showcase demo shows catalog items beneath the main image in an example Instagram ad.
The Details:
One ad image can turn into a product display. A retailer’s catalog is the product list it shares with Meta. With Product showcase, the main image or video can appear above a row of catalog items a shopper can swipe through. On version 27, Meta may add that row to a new ad when the advertiser’s software leaves the showcase setting blank and Meta is confident a set of products matches the ad. Picture a retailer submitting a jacket ad and Meta adding a row of related products from its catalog. The retailer’s software can explicitly opt out. Earlier versions keep their existing behavior for this setting.
A device choice can become a starting point. An ad set is a group of ads that share delivery settings. On version 27, if an eligible new ad set for a sales campaign names specific phones or operating systems but leaves the expansion setting blank, Meta can show those ads on other mobile devices when it expects better results. To keep delivery within the original device choices, the software has to send a zero for device expansion. The change leaves out existing ad sets, ad sets that count conversions in a mobile app, and Meta’s special ad categories, such as housing. Meta expects the default to reach older versions in about 90 days, with the date still to be confirmed. That window also applies to a separate rule for new lookalike audiences, which help advertisers reach people similar to an existing audience. Software must stop sending location fields when it creates one. The ad set that uses the audience already determines where it can run.
Catalog updates have their own deadline. A retailer or agency can send several catalog changes in one request, such as updating product details after a merchandising change. Version 27 stops accepting the old batch request. Meta points integrations to its replacement catalog update method, which can group additions, edits and deletions. The replacement also expects some data in a different format, including how software submits product images. The older method works on version 26 and earlier until Meta ends version 26 support.
MarketMaze Take: The change makes the settings sent by an agency’s software part of what a retailer is approving. An approved jacket image says little about which other products should appear beside it. A test intended to measure how an ad works on a particular phone can also become harder to interpret if some of the impressions go to other devices.
A broken catalog update gives the integration team an error to investigate. The same team can submit an ad successfully while allowing Meta to make those other decisions. That calls for different checks. Catalog teams need to verify which updates went through. Media and merchandising teams need to know what the software leaves up to Meta and where they want it to send an explicit choice. The release gives no figures on how often products will be added or how much delivery might shift.
