iOS might be the “world’s most advanced mobile operating system,” according to Apple, but it isn’t the most reliable, according to a new study.

New data shows that iPhone’s “performance issues and high failure rates” over the last year make Android more stable. iPhone 6 and iPhone 6s are said to be two of the worst-performing Apple handsets.

Android still gets criticized for being insecure and unreliable, but with the significant improvements Google made in recent years, that’s no longer the case. This is proven by the latest State of Mobile Device Performance and Health report from Blancco, a trusted security firm certified and recommended by 18 national and international governing bodies.

Blancco’s State of Mobile Device Performance and Health report is published every quarter based on data obtained from its own diagnostics platforms. “The information contained in this report is based on internal data collected from millions of iOS and Android smartphones and tablets that underwent diagnostics testing on our platform in North America, Europe and Asia during the fourth quarter of 2016 (Q4 2016),” Blancco says in an introduction to the study’s results.

iPhone failure rate rises

Blancco’s “failure rate” stats took into account problems with hardware as well as software, including the reliability of third-party apps developed for the two platforms.

While Android’s failure rate has improved over time — from 85 percent in Q4 2015 and 44 percent in Q1 2016 to 35 percent in Q2 2016 — iPhone’s has been rising. In Q4 2015, the failure rate of iOS was just 15 percent. But as of Q4 2016, it stands at a staggering 62 percent.

iPhone 6 has been the worst-performing handset for four consecutive quarters, but iPhone 7 and iPhone 7 Plus “aren’t exempt from problems,” Blancco says. Crashing apps, overheating and headphone malfunctions are the most common issues among iPhone users.

Facebook, Instagram and Snapchat — three of the most popular social media apps — were discovered to be some of the most unreliable apps on iPhone last year, with users plagued by frequent crashes.

On Android, the most common problems were related to the camera, USB port and carrier signal glitches. Samsung devices have suffered the highest failure rate among Android devices for five quarters in a row, but Samsung’s rate was still significantly lower than iPhone’s (16 percent) during Q4 2016.

Blancco’s Repair Mobile Diagnostics Solution, which supports Android and iOS, helps businesses identify problems with smartphones and tablets before they get resold on the second-hand market.