Why is my app crashing on Android?

We’ve all been there before – happily using an app when suddenly it freezes, disappears, and you’re kicked back to the home screen. Those unexpected crashes and “Application Not Responding” popups are a frustration shared by Android users everywhere. Studies show that mobile apps crash an average of 2-3% of the time, with some apps crashing over 5% of sessions. For popular apps with millions of users, that translates to thousands of crashes per day.

So what causes apps to crash unexpectedly on Android? There are a number of technical reasons, both within the app’s code and on the device itself, that can lead to instability and crashes. This article will provide an overview of the most common culprits, including memory management issues, resource conflicts, unsupported APIs, security issues, device fragmentation, problems with third-party SDKs, and more. Understanding why apps crash enables developers to build higher quality apps, and helps users troubleshoot and prevent annoying crashes.

Software Bugs

Bugs in the app code are one of the top reasons for app crashes on Android. These bugs occur due to mistakes in the programming logic that cause the app to behave unexpectedly. Some of the most common types of bugs that can lead to crashes include:

Null pointer exceptions – These happen when the app tries to access an object that doesn’t exist or was not initialized properly. This leads to a crash as the app doesn’t know how to handle the null object. According to Shake, null pointer exceptions are one of the most frequent crashes in Android apps.

Race conditions – These occur when the timing or order of events affects the app’s behavior in an unintended way. For example, if two threads try to access the same resource simultaneously without synchronization, it can corrupt data and cause a crash.

Improper exception handling – An uncaught exception that is not handled properly will lead to an abrupt app crash. Proper exception handling and recovery is important to provide a smooth experience.

Resource leaks – Failing to release resources like cursors, connections, etc. can slowly eat up memory over time and eventually lead to an out of memory crash.

Infinite loops – These will lock up the app and kernel watchdog timeouts will forcibly close the app after a period of unresponsiveness.

Bugs like these occur due to programming oversights, and extensive testing is required to catch them before release. Following best practices around memory management, multithreading, exception handling can help minimize crashes from software bugs.

Memory Issues

Not properly managing memory allocation and use can lead to crashes on Android devices. One common memory-related problem is memory leaks. A memory leak happens when an application allocates memory for an object but fails to free up that memory when the object is no longer needed. Over time, as unused objects accumulate, the app consumes more and more memory. This can slow down performance, trigger the system to kill background processes, or lead to the app crashing entirely.

Memory leaks frequently occur due to issues like maintaining unnecessary references to objects that won’t be reused, failing to clean up singletons or static variables, or not closing resources like cursors and listeners. For example, if an Activity loads a large bitmap but does not free the memory when transitioning to other Activities, that bitmap will remain in memory indefinitely. Each time the user opens and closes this Activity, more memory is leaked.

To prevent memory leaks, developers should profile memory usage, look for spikes over time, and carefully manage object lifecycles. Releasing references to unused objects, closing resources properly, and avoiding static contexts for long-lived objects can all help minimize leaks. Optimizing images, caching intelligently, and freeing memory on low-memory signals are other important techniques.

With careful memory management, developers can optimize performance and prevent the crashes or instability that stem from memory issues on Android devices.

Resource Conflicts

One common cause of app crashes on Android is resource conflicts. This occurs when two or more apps or components try to access the same resource simultaneously, such as the camera or Bluetooth. Here are some examples of resource conflicts that can cause crashes:

Trying to take a photo or record video using the camera when another app is already accessing it can lead to the app crashing with an error like “Camera in use”. This happens because the camera is a shared resource that can only be accessed by one app at a time [1]. The same applies to other hardware like the microphone, GPS, or Bluetooth.

Bluetooth can also only be used by one app at a time. If App A initiates a Bluetooth connection while App B is already connected, App B may crash when it tries to read or write Bluetooth data. Apps must properly check if Bluetooth is already in use before trying to access it.

Conflicts can also occur between app resources like custom Views, Drawables, or String values defined in an app and its libraries. If the app and library define resources with the same name, the build will fail or crash at runtime because it won’t know which one to use [2]. This can be avoided by using namespacing for app resources.

Unsupported APIs

One common cause of app crashes on Android is using newer APIs that are unsupported on older Android versions. Each Android version introduces new APIs, but older devices may not support those newer APIs. If your app calls an API that doesn’t exist on the user’s Android version, the app will crash with an “Unsupported API level” error.

For example, trying to use the Camera2 API introduced in Android 5.0 on a device running Android 4.4 will cause a crash. The device simply doesn’t support that newer Camera2 API.

To prevent this, you need to check the API level that your app is running on and only call APIs that are supported:

“You can check the API level at runtime by calling Build.VERSION.SDK_INT. Then wrap calls to newer APIs in an if statement checking the API level.”

You should also use Lint in Android Studio to statically check that you don’t call unsupported APIs. Lint will warn you if you try to use an API that wasn’t introduced until a later Android version.

Checking API levels and using Lint ensures your app won’t crash from using newer APIs on older Android versions that don’t support them yet.

Security Issues

Malware and viruses can infect apps and cause them to crash unexpectedly. Malicious code may exploit vulnerabilities in an app to gain access to sensitive data or system resources. According to the Android developer documentation, “An Android app crashes whenever there’s an unexpected exit caused by an unhandled exception or signal.”

Developers should follow best practices to secure their apps and reduce the risk of crashes. Some recommendations include:

• Using the latest Android SDK and keeping dependencies up-to-date
• Following secure coding guidelines and performing security testing
• Enabling proguard to obfuscate code and remove unused code
• Validating all inputs from external sources and sanitizing outputs
• Avoiding the use of insecure components like WebViews
• Requesting only necessary permissions and minimizing access to privacy-sensitive data
• Implementing certificate pinning when connecting to remote servers
• Encrypting sensitive information stored locally

Implementing security best practices during development can reduce the risk of malware infection and crashes. Developers should also submit apps to Google Play Protect to scan for potentially harmful applications.

Device Fragmentation

Android is known for having a huge range of devices with different hardware specifications. With over 24,000 distinct Android device models available as of 2019 (source), it can be challenging for developers to ensure their apps work properly across all devices.

Fragmentation occurs because various manufacturers like Samsung, LG, Motorola etc.customize the Android OS on their devices. Each hardware vendor implements Android differently with changes to the OS framework, drivers, preinstalled apps etc. This leads to inconsistencies in features and performance.

Hardware differences like screen size, resolution, CPU, GPU, memory and sensors can cause compatibility issues and crashes. An app running smoothly on a high-end device may fail on a low-end budget device. Bugs may occur on some chipsets that don’t happen on others.

To prevent crashes from device fragmentation, extensive testing on a diverse range of devices is recommended. Emulators alone are not sufficient since they cannot fully simulate real hardware. Try to test on both flagships and low-end devices across multiple manufacturers to catch any device-specific bugs.

Third-Party SDKs

Integrating third-party SDKs into your Android app can be a source of crashes if they contain bugs or are incompatible with your app. As noted in the Android Studio known issues page, “Issues in third-party plugins can also affect your project” (https://developer.android.com/studio/known-issues). Before integrating an SDK, be sure to thoroughly test it within your app’s codebase across a range of devices. Refer to the SDK provider’s documentation and changelog to check for known issues. If your app crashes only when utilizing a specific SDK, try removing it as a troubleshooting step to isolate the cause. With careful testing and vetting, third-party SDKs can provide useful functionality without compromising stability.

How to Prevent Crashes

App crashes can be extremely frustrating for users, but there are ways for developers to minimize crashes through best practices:

Extensive testing before releasing an app is critical to catch bugs and errors that could lead to crashes. Testing on a variety of devices and Android versions helps uncover issues that may only happen under certain conditions.

Using analytics and crash reporting gives insight into situations that are causing the app to crash. This data allows developers to replicate crashes and address underlying problems in the code or functionality.

Frequently updating apps with bug fixes and performance improvements reduces the likelihood of crashes over time. Staying on top of user feedback helps identify recent issues to be addressed in updates.

Following Android’s best practices for design and development also lowers the chance for crashes. Using up-to-date APIs, avoiding known memory leaks, releasing resources properly, and handling edge cases are all important development techniques for stable apps.

Conclusion

In this article we explored some of the most frequent causes of app crashes on Android, including memory problems, device fragmentation issues, third-party SDKs, and security vulnerabilities. While crashes can originate from a variety of sources, they ultimately point to problems with software quality that developers must make a priority to address.

By being aware of crash-prone areas like memory management, unsupported APIs, and SDK integrations, developers can proactively improve their app’s stability. Rigorous testing across the wide spectrum of Android devices is also key to avoiding fragmentation-related crashes. Implementing crash analytics and monitoring tools can provide valuable insights into why and where apps fail in the real world.

No app is crash-proof, but developers have many techniques at their disposal to bolster stability and robustness. By making app quality a top concern throughout the development lifecycle, many common crash pain points can be avoided, leading to happier users and better ratings/reviews. The ultimate goal is to maximize uptime and minimize disruptive crashes to create a smooth, reliable user experience.