Mobile Apps’ released Favoriting in November. A small bug caused an edge case crash. Here’s how we used our Mobile APM product to fix it.
The Mobile Apps team recently released a Favoriting feature, allowing users to favorite their most important applications so those applications would always be at the top of their list. After testing, the updates were released to the Apple App and Google Play stores.
The night after the Android updates were released, an alert showed up on our lead Android developer’s phone. He clicked on the alerts notification on his phone, which opened the New Relic App and brought him to the Alert page. The newly released version was popping up and it was clear that some users were seeing crashes.
From here he went to his Desktop and opened up the Mobile APM Dashboard , going straight to to look at Crashes and sure enough, the new version - 2.9.3 - showed climbing Crashes. He then filtered to this newly released version and reset the time picker to 24 hours.
The developer then went to Crash Analysis , which handily maintained his filters, and looked at the Crash Types by Count. There were around 170 crashes in the top crash bar, so there was clearly bad code. He clicked on the associated link in Crash types, opening a Crash Type Summary which indicated the Exception, Location and Message.
He could also follow the stack trace to quickly understand where users were impacted.
The problem was that we had attached the notification of the new favoriting feature to the second row in the application list, but not everyone has more than one row. Those who only have one application listed were experiencing crashes with the new release.
A Hot Fix was released in under an hour and the Crash Rate quickly de-escalated to 0.2%.