Mobile Apps Testing

Most Common Bugs Found on Mobile Apps

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Your mobile device is a hub of competing technologies and platforms that work in unison to present you with a coherent and enjoyable user experience. However, the complexity of internal and external interactions between these components can cause unforeseen problems with mobile applications that are not adequately tested. PLUS QA started testing mobile apps in 2008, the same year Apple released the first iPhone. We have experience testing with a wide range of mobile devices from various manufacturers and operating systems, including iOS and Android. During our decade-plus of testing, we’ve identified the most common bugs that can develop on mobile apps.

Display Issues

Device screens are as varied as their owners. They come in all shapes, sizes, and resolutions – you must consider an enormous range of potential visual interpretations of your application or website when testing. One way to find issues with uncommon screens is to conduct thorough compatibility testing across a vast catalog of devices.

An illustration of multiple device types displayed near each other. All of the devices have a checkmark displayed on their screen representing cross device compatibility.
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Users operate their mobile devices with varying display orientations. Issues can arise when switching between horizontal and vertical orientations. In some cases, switching may cause interface elements to crash. Testing an app in both portrait and landscape orientations on multiple devices can help avoid these problems. If you’re building a device library for testing device compatibility, you can learn more about how we manage our robust device library on our resources page.

Poor Performance

Users demand lightning-fast response times with their mobile devices. The same is true of their app usage. Executing various forms of testing, like load and stress tests, are essential to ensure peak performance. When applications don’t launch in the first 5-10 seconds, users will assume that there is a problem, sometimes leading them to close or even uninstall the app. Worse yet, if the app is unable to launch, most users will not give it a second chance. As we explained in our latest E-Commerce Testing Guide, such a failure could negatively impact your entire brand, not just your app.

Operating System Incompatibility

Users can be slow to update their operating systems, especially Android users – just 6% had updated to Android 13 in the five months that followed its August 2022 release. It’s important to consider recent variations of device operating systems during your app’s designing and testing phases. Simply put, more OS variations mean more potential users.

Why Your Android Phone Won't Download New Apps, And How To Fix It
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Every year PLUS QA evaluates user adoption statistics for Android and iOS devices to predict better what operating systems to test that year. We often find that many users, not just Android, will wait before upgrading their devices – despite security and performance benefits. In some cases, users still own devices that cannot be upgraded to the newest OS version. While you might not be able to account for every scenario, adoption statistics can be a helpful guide for selecting which to support. For more information on what devices and operating systems you should consider, check out our 2023 device guides for iOS and Android platforms.

Battery Drain

TikTok, Netflix, Candy Crush Saga, and text threads packed with family pics are real battery drainers, but those features are why people love using mobile devices. People will allow those apps to drain their phones until the LOW BATTERY notification arrives, while other apps don't receive the same lenience. If an app is a power drainer and causes devices to die faster, users are more likely to remove that app. iOS and Android have "Battery Usage" settings that allow users to see what percentage of their device's power an app has used since the last full charge. It makes sense to test how excessive your app's battery drain is by comparing it to similar apps. Also, consider gauging the battery drain when it's active versus put into the background. Excessive battery drain could come from several sources -- it's important to identify any active permissions like location, network, and notifications that significantly impact the device's battery life.

Form Validation Issues

Applications use form validation to ensure users have correctly entered the necessary information. When a form has any requirements that might prevent a user from moving forward – like a blank field or invalid email address –- it is critical that a corresponding message informs the user why the error occurred. The application must display an error message if a user is missing text or the entered data doesn't meet the form requirements, only allowing the user to move forward if all inputted data is correct. Our pals over at GeeksforGeeks put together a handy gif that perfectly encapsulates what we mean.

Demonstration of bugs users experience while using a form on a mobile device.
Image Credit: GeeksforGeeks


Our smartphones are filled with useful but competing apps that serve you in many ways. They send us notifications, allow incoming calls and texts, and prompt us when the battery is low. When this happens, your app should be able to anticipate and adapt to the interruption. If your app is unable to handle such interruptions, it could cause the app to crash or function poorly, which impacts the user experience. If it’s a common issue, a user who was hoping to remain engaged with your app might just give up on it entirely. This is why interruption tests are treated as a core part of functionality testing for mobile apps.

Unnecessary Permissions

Mobile apps can come with various features that might require user-granted permissions to function. These can include enabling access to the user's location, camera, microphone, and other device capabilities. Users are sensitive to having their personal data collected. Applications must limit access permissions to those necessary for the app to work and ensure permissions are only engaged when the application is in use. Unnecessary access to people's data and bugs where applications turn on cameras or microphones while users aren't involved can erode user trust and contribute to a poor overall perception of your app.

Screenshot of the permissions menu for the Amazon Shopping app.

Incompatible Gestures

Different phones use different gestures for functionality, such as swiping, tapping, and pinching. The use of gestures changes when assistive technologies like VoiceOver or TalkBack are engaged. It’s essential to test on devices from various manufacturers and include accessibility testing to prevent the app from reacting strangely to unsupported gestures. It could be more than a simple usability issue and might prevent access to people with disabilities who rely on less common gestures.


Mobile apps have become an important part of our lives – benefiting us socially, professionally, and personally. App makers face a lot of competition – there are more than two million apps in the iPhone store. Avoiding common bugs can help set you apart from the competition in app stores and ensure your users remain happy with your app’s performance. This is true for websites as well – check out our blog about the most common bugs found on websites. Make sure to optimize your app with this list in mind, or reach out to us for help!

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