ad blockers ecommerceAd blockers threaten to disrupt the holiday shopping season and make life miserable for digital marketers.

Already becoming increasingly popular, ad blockers may become pervasive since Apple’s new iOS 9 operating system allows users to easily install them from its app store. Ad blockers are some of the most popular apps in the App Store. Apps like Crystal, Purify, Blockr and Weblock were downloaded more than 500,000 times in the operating system’s first week.

When Crystal, one of the most popular ad blockers, was installed, an iPhone couldn’t fully render e-commerce websites of major retailers, including Walmart, Sears and Lululemon, according to Fortune.  

“This upcoming holiday season… content-blockers are going to cause a lot of problems,” Branding Brand CEO Chris Mason told Fortune.

For example, depending on the ecommerce site, mobile phone users will not see images, will be unable to add items to online shopping carts, or will see no content whatsoever. Shoppers may mistakenly conclude that the website is malfunctioning.

Retailers may be unable to collect data. Google Analytics or Adobe’s Omniture may not function with ad blockers installed.

The Holiday Rush is on

Retailers may be able to fix problems with extensive recoding. However, they are running out of time ahead of the holiday shopping season. Many freeze their codes on Nov. 1, Mason says.

The issue is especially worrisome considering the robust growth of mobile e-commerce and consumer preference for purchases through iPhones rather than Android devices. Mobile commerce accounted for over a fifth (21.9%) of online shopping on cyber Monday last year, the Monday after Thanksgiving, an increase from 15.9% the previous year, eConsultancy reports. Most of those transactions (78%) occurred through Apple’s iOS.

Even if retailers fix issues caused by one ad blocker, they may encounter other problems caused by another app in a kind of whack-a-mole battle. Retailers may need to work directly with ad blocker firms directly to resolve software issues.  Brands will be forced to constantly test their e-commerce systems with different ad blockers just as they now test their sites on different browsers.

Some observers wonder if Apple will reconsider its decision and disallow ad blockers after it sees the e-commerce havoc they cause. Given consumers’ distaste for online ads, especially on mobile devices, Apple is unlikely to do so. Besides adding unwanted clutter, online ads slow page load times and decrease battery lives of smartphones. Apple’s competition with Google which gains much of its income through online ads also motivates Apple to allow ad blockers.

A Disruption to the Internet’s Business Model

An overriding problem of ad blockers is that they threaten to disrupt the Internet’s business model. Web publishers depend on advertising for income. Without ads, online news outlets and web publishers will be unable to pay to costs associated with news coverage and content creation.

Some companies may pay ad blockers to allow their ads to appear in a practice called “whitelisting.”

Publishers may counter the threat by creating ads that load faster and integrate better into their websites. An ad blocking app by the New York Times revealed a discrepancy of how publishers integrate ads. Some publishers appear to carefully consider how ads affect the performance of mobile phones; others seem not to care.

Other publishers may take a more aggressive approach by attempting to block ad blockers. The Washington Post was testing how to send visitors to a subscription page if they have an ad blocker installed.

“Many people already receive our journalism for free online, with digital advertising paying only a portion of the cost,” a Washington Post spokesperson told BuzzFeed News. “Without income via subscriptions or advertising, we are unable to deliver the journalism that people coming to our site expect from us. We are currently running a test using a few different approaches to see what moves these readers to either enable ads on The Washington Post, or subscribe.”

Bottom Line: Problems with ecommerce sites loading on iPhones with ad blockers installed raise serious concerns for mobile marketers and publishers. All brands using digital advertising and companies with e-commerce sites must be aware of the potential problems and test their sites to identify and resolve problems before the holiday shopping season.