Firebase Bug Crashed Thousands of iOS Apps at Launch

A faulty response from a Google server made apps crash the moment they opened on Monday night, and developers reported thousands of iOS apps affected. Google says the problem is fixed and developers do not need to ship an update.

The culprit was Analytics for Firebase, the analytics component many iPhone apps bundle. Because the bug sat in a shared SDK, apps from unrelated developers could fail at the same time.

What went wrong

According to Google's Firebase status page, the iOS SDK received an incorrectly formatted experiment-configuration payload from a Google endpoint. The SDK then tried to parse it into a dictionary with a nil key, and the app crashed at launch.

Timeline and cleanup

The incident began at 17:41 PDT on Monday, September 28. Google had the fix fully rolled out at 19:52 PDT, about two hours and eleven minutes later.

That did not end the crashes for everyone. Because of caching, some app instances could keep crashing for up to four hours after the rollout. Since the fix is on Google's side, developers need no new SDK release.

How big was it

Google has not published a figure for affected apps or users. The "thousands of apps" number comes from developer reports and is not confirmed beyond that. No impact on Android was reported.

The incident shows how one third-party SDK, fed by a single remote response, can take down Apple apps that otherwise have nothing in common.