iOS 27 has been available to the public since September 14, marking a significant update for the iPhone ecosystem. While many users report smoother performance compared to the previous version, a subset of owners are experiencing a range of technical issues. These range from minor annoyances like keyboard lag and Home Screen glitches to more critical problems such as cellular failures and unexpected restarts on the new iPhone 18 Pro models. For technical readers, understanding the root causes and applying the correct fixes is essential to maintaining device stability.
Understanding the Post-Update Landscape
It is important to note that not every iPhone running iOS 27 exhibits these problems. Community discussions on platforms like Reddit and Apple’s Support Community indicate that many devices are functioning normally or even better than on iOS 26. However, for those encountering bugs, the issues are distinct and often model-specific. Apple has acknowledged the severity of certain bugs, particularly those affecting the latest hardware, and has confirmed that a software update is in development.
Critical Fix: Face ID and Restart Loops
The most significant confirmed issue currently affects specific units of the iPhone 18 Pro and iPhone 18 Pro Max. Users have reported that Face ID fails during app authentication, leading to a system freeze and an immediate restart. In some cases, panic logs are generated after repeated crashes, indicating a deeper system instability.
Apple has confirmed that it plans to release a software update to address the problem involving Face ID and unexpected restarts on the iPhone 18 Pro and iPhone 18 Pro Max.
While iOS 27.0.1 is currently in testing and expected to be the first bug-fix release, users can apply a temporary workaround. Resetting Face ID is the recommended immediate step. This involves navigating to Settings, selecting Face ID & Passcode, tapping Reset Face ID, restarting the device, and then re-enrolling the biometric data. This process often clears the corrupted authentication state causing the crashes.
Addressing Battery Drain and Overheating
Battery drain is one of the most common complaints following the iOS 27 installation. Reports from iPhone 17 Pro and iPhone 15 Pro Max owners describe unusually high power usage. However, technical analysis suggests that this is often a normal part of the post-update process rather than a persistent bug.
Apple explains that background tasks, such as file indexing and device setup completion, continue after a major update. The Battery page may display an “Ongoing iOS Update” notice during this period. To mitigate this, users should wait several days before assessing battery life. Practical steps include checking Settings > Battery to identify power-hungry processes, restarting the device after indexing completes, and ensuring all apps are updated via the App Store. If the device remains hot while idle after the indexing period, it may indicate a genuine thermal issue requiring further attention.
Resolving Keyboard and Interface Glitches
Several users have reported that the stock keyboard feels sluggish, particularly within the Messages app. Symptoms include delayed key animations, slow haptic feedback, and missed inputs. Since there is no confirmed system-wide fix yet, restarting the phone is the simplest initial remedy. Additionally, disabling Keyboard Feedback under Settings > Sounds & Haptics > Keyboard Feedback has been reported to improve typing responsiveness. Testing with haptics and sound disabled can help determine if the feedback mechanism is the source of the lag.
Visual glitches are also prevalent, particularly with the new Liquid Glass customization features. Users report stuttering when tinted or transparent icons are enabled, as well as blank Home Screen folders and flickering widgets. The most effective workaround is to switch back to standard app icons and remove any affected widgets. Restarting the device after these changes often resolves the interface jitter.
Fixing Connectivity and Auto-Brightness
Cellular connectivity issues have been reported across multiple models, including the iPhone 14 Pro, iPhone 15 Plus, and iPhone 18 Pro Max. Symptoms include unreliable mobile data and an inability to place calls. Apple recommends toggling Airplane Mode and restarting the device. If the issue persists, resetting network settings via Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings can clear damaged configurations, though this will remove saved Wi-Fi passwords and VPN settings.
Auto-brightness reliability has also been compromised for some iPhone 15 Pro owners, with displays remaining too dim outdoors or too bright indoors. Toggling Auto-Brightness off and back on under Settings > Accessibility > Display & Text Size > Auto-Brightness has temporarily restored normal behavior for many users.
Conclusion
While iOS 27 introduces new features and performance improvements, it also brings a set of bugs that require specific troubleshooting. By following the steps outlined above, users can mitigate issues related to battery, biometrics, and connectivity. Readers should monitor for the release of iOS 27.0.1, which is expected to address the most critical Face ID and restart issues on the iPhone 18 Pro series. Until then, applying these workarounds will help maintain a stable and efficient user experience.