Spend less time managing your business and spend more time doing what you love. Regain control now!

A Mysterious Bug is Causing Links to Fail on iOS

Over the weekend, 9to5Mac reported what appears to be a widespread iOS bug that causes links to fail to open. In some cases, long pressing links crashes the app containing the link. What’s worse, rebooting your iOS device or uninstalling third-party apps affected by the bug seems to only correct the problem temporarily.

Ben Collier has been doing some digging and it looks as though the culprit may be Shared Web Credentials, a means by which websites and apps can share login credentials. As Ben explains:

In iOS 9 Apple introduced Universal Links, these allow app developers to associate their website and app, so links to the website can open the app up automatically if installed. For example, following a link to a Guardian article opens up the Guardian app to that specific article instead of their website.

App developers put an app association file on their website which lists which types of URLs the app can open. When you install an app, iOS downloads this associated file and updates your own database of what URLs your installed apps can open. The website and app listing in iTunes are linked by the developer - so it prevents anyone from hijacking your website with their app.

When you tap a link in iOS, the system looks through the database of installed apps supported URLs to see if it matches a pattern an installed app can handle. If nothing matches it opens it up as a standard app.

9to5Mac has been able to replicate the bug by installing the app, which until today, had an unusually large association file. The bug does not appear to be limited to the app, but the unusual size of its association file lead to initial speculation that file size was the culprit. However, further investigation suggest that the problem may be with the Shared Web Credentials daemon itself and is either triggered by a large association file, or becomes corrupt regardless of the size of association files. Whatever the cause, let’s hope that a reliable workaround is found soon and that Apple releases an iOS update that fixes the problem.

We have reached out to Apple for comment regarding the bug and will update this post with whatever additional information we learn.

[Update: 2016-03-29] Based on follow up reports by 9to5Mac and Ben Collier, it appears that large association files are indeed the source of the bug that that causes links to fail to open for some iOS users. According to 9to5Mac:

Sources tell us that Apple is working with high-profile developers to help them understand and better use the universal links APIs.

9to5Mac also quotes a statement it received from Apple PR:

“We are aware of this issue, and we will release a fix in a software update soon.”

Whether the source of this quote is the same as the sources that reportedly told 9to5Mac that Apple is working with ‘high-profile developers’ is unclear.

9to5Mac also reports that the Wikipedia app and Eat24 apps may also trigger the link bug. Unfortunately, there is still no known workaround for the issue. Nor is there a way to tell which apps are affected before installing them.

Ben Collier, whose post yesterday pinpointed the source of the bug, has posted a fix that requires users to complete a dozen steps. The fix appears to be dependent on the timing of the steps, which means that it may require multiple attempts to get it to work.

Unlock More with Club MacStories

Founded in 2015, Club MacStories has delivered exclusive content every week for over six years.

In that time, members have enjoyed nearly 400 weekly and monthly newsletters packed with more of your favorite MacStories writing as well as Club-only podcasts, eBooks, discounts on apps, icons, and services. Join today, and you’ll get everything new that we publish every week, plus access to our entire archive of back issues and downloadable perks.

The Club expanded in 2021 with Club MacStories+ and Club Premier. Club MacStories+ members enjoy even more exclusive stories, a vibrant Discord community, a rotating roster of app discounts, and more. And, with Club Premier, you get everything we offer at every Club level plus an extended, ad-free version of our podcast AppStories that is delivered early each week in high-bitrate audio.

Choose the Club plan that’s right for you:

  • Club MacStories: Weekly and monthly newsletters via email and the web that are brimming with app collections, tips, automation workflows, longform writing, a Club-only podcast, periodic giveaways, and more;
  • Club MacStories+: Everything that Club MacStories offers, plus exclusive content like Federico’s Automation Academy and John’s Macintosh Desktop Experience, a powerful web app for searching and exploring over 6 years of content and creating custom RSS feeds of Club content, an active Discord community, and a rotating collection of discounts, and more;
  • Club Premier: Everything in from our other plans and AppStories+, an extended version of our flagship podcast that’s delivered early, ad-free, and in high-bitrate audio.