Common UI Bugs in Web Applications and How to Fix Them

What Are UI Bugs?

UI bugs are flaws in a web application's interface that affect how users see or interact with content. They can appear as visual inconsistencies, misaligned elements, broken buttons, or unexpected behavior in interactive components. These bugs can be caused by coding errors, browser compatibility issues, or even untested design changes.

While some UI bugs are minor and purely aesthetic, others directly impact usability and functionality. For example, a form field that doesn’t accept input or a button that fails to trigger an action can prevent users from completing critical tasks, leading to frustration and potential loss of engagement.

Why UI Testing Matters for User Experience

UI testing ensures that web applications function correctly and look consistent across different devices and browsers. It helps teams catch issues that could frustrate users, interrupt key tasks, or reduce overall engagement.

Here are the key reasons why UI testing is essential:

• Ensures Task Completion: UI testing verifies that all interactive elements, such as forms, buttons, and menus, work as intended, preventing users from abandoning important actions like purchases or sign-ups.
• Preserves Design Integrity Across Devices: Testing reveals layout shifts, overlapping elements, or scaling issues that could compromise the intended visual hierarchy on desktops, tablets, and mobile screens.
• Detects Hidden Functional Flaws: Some issues, like broken event triggers or delayed page responses, may not be immediately visible but can significantly disrupt workflows if left untested.
• Validates Cross-Browser Behavior: UI testing identifies inconsistencies in how browsers render HTML, CSS, and JavaScript, preventing scenarios where features work in one browser but fail in another.
• Supports Accessibility Compliance: Testing ensures that all users, including those relying on screen readers or keyboard navigation, can interact with the application as intended.
• Reduces Post-Release Maintenance Costs: Catching UI bugs during development prevents expensive patches, emergency hotfixes, and reputational damage caused by negative user experiences.

14 Most Common UI Bugs in Web Applications

UI bugs can appear in many forms, affecting both the look and functionality of a web application. Identifying these issues is essential for maintaining a seamless user experience. Below are the most frequently encountered UI bugs, with detailed explanations:

1. Alignment and Spacing Issues

Elements like buttons, images, or text blocks may be misaligned or unevenly spaced. These issues often occur due to inconsistent CSS, margin/padding errors, or responsive design failures. Misaligned elements can make the interface feel unprofessional and confuse users about which actions are available.

2. Broken Buttons and Links 

Buttons or hyperlinks that do not respond when clicked are a critical usability problem. They usually result from incorrect event handlers, missing routes, or JavaScript errors. Users encountering broken buttons may abandon key actions, such as completing a purchase or submitting a form.

3. Overlapping Elements

When UI components overlap, such as text covering images or menus covering buttons, users may be unable to access certain features. This commonly occurs due to fixed positioning issues, z-index conflicts, or scaling problems on smaller screens.

4. Responsive Design Failures

Web applications may render perfectly on desktops but break on tablets or smartphones. Problems like cut-off content, horizontal scrolling, or squeezed layouts often result from inadequate media queries or flexible grid misconfigurations. Poor responsiveness frustrates users and reduces accessibility on mobile devices.

5. Font and Style Inconsistencies

Inconsistent typography, colors, or button styles across pages can create a disjointed experience. These issues typically stem from missing style variables, outdated CSS, or improper overrides. Users may perceive the application as unpolished or unreliable.

6. Form Field Errors

Input fields that fail to accept data, display incorrect validation messages, or reset unexpectedly are a common issue. These bugs often arise from misconfigured form validation scripts or back-end communication errors. They directly hinder task completion, such as signing up or making payments.

7. Missing Images or Icons 

Images or icons failing to load due to broken URLs, server issues, or lazy-loading errors leave the UI incomplete. This can reduce clarity, make pages feel unfinished, and negatively affect user trust.

8. Scroll and Overflow Problems

Content that does not scroll correctly or overflows outside its container can prevent users from accessing information. These bugs often originate from fixed-height containers, CSS overflow misconfigurations, or dynamic content loading errors.

9. Popup and Modal Malfunctions

Popups or modal dialogs may fail to open, close too quickly, or block other content unexpectedly. Issues often arise from JavaScript timing conflicts, z-index mismanagement, or asynchronous event handling errors. Users encountering these problems may miss important messages or abandon processes.

10. Animation and Transition Glitches

Animations that jitter, lag, or freeze can distract users and make interactions feel unreliable. These issues typically come from heavy DOM manipulation, unoptimized CSS transitions, or performance bottlenecks. Smooth animations are critical for a polished, professional interface.

11. Browser-Specific Rendering Issues

Web pages may appear differently in Chrome, Firefox, Safari, or Edge due to variations in how browsers interpret CSS, HTML, and JavaScript. Without thorough cross-browser testing, features may fail or appear broken in certain environments, alienating users on specific platforms.

12. Menu and Navigation Problems

Dropdowns, side menus, or navigation bars may fail to expand, collapse, or respond correctly. These issues often result from JavaScript event conflicts or improper CSS handling. Navigation problems make it difficult for users to explore and complete tasks efficiently.

13. Loading and Placeholder Errors

Spinners, loading bars, or placeholder elements that fail to appear or disappear correctly can create confusion. Users may perceive the application as slow, broken, or unresponsive. Common causes include asynchronous data fetching errors or improper state management.

14. Accessibility Failures

Elements that cannot be accessed via keyboard navigation, screen readers, or assistive technologies significantly impact users with disabilities. These issues arise from missing ARIA attributes, improper focus handling, or insufficient semantic markup. Ignoring accessibility reduces the audience that can effectively use the application and can create compliance risks.

Visual UI Bug Examples in Popular Applications

Even major platforms experience UI bugs that affect usability and visual consistency. Examining these examples highlights common issues and the importance of thorough testing.

1. Amazon Mobile App – Purchase Process Issues

In the Amazon mobile app, some users experience buttons or interactive elements in the purchase flow failing to respond on certain devices. For example, the “Proceed to Checkout” button may appear clickable but does not trigger the next step, leaving users stuck in the cart. These issues often arise due to inconsistencies in event handling across different operating systems or device resolutions. Such UI bugs directly impact conversions, as users may abandon their carts out of frustration.

2. Southwest Airlines – Continue Button Overlay

On Southwest Airlines’ booking interface, the “Continue” button sometimes overlays other page content on smaller screens or mobile devices. This can block access to other form fields, making it difficult for users to complete their flight booking. The underlying cause is usually fixed positioning conflicts combined with insufficient responsive design testing. Problems like these disrupt the user journey, reduce satisfaction, and increase the likelihood of errors during critical actions.

3. Google Homepage – Rendering Problems

Even Google’s homepage occasionally exhibits UI glitches in specific browser versions. For instance, overlapping search suggestions or misaligned input fields have been reported, which can confuse users and hinder efficient searching. These rendering issues often occur due to differences in how browsers interpret CSS and JavaScript, highlighting the importance of cross-browser testing. On a high-traffic platform like Google, even minor UI inconsistencies can affect millions of users and degrade trust in the product.

4. LinkedIn – Privacy Settings Overlap

LinkedIn’s account settings sometimes display overlapping elements when adjusting privacy options, especially on smaller screens or at certain browser zoom levels. Checkboxes and dropdowns can become partially hidden, making it difficult for users to configure settings accurately. This type of UI bug usually stems from inadequate handling of dynamic layouts or improper container sizing. Such errors not only frustrate users but can also lead to mistakes in privacy management, impacting user confidence and security.

These real-world examples illustrate that visual UI bugs can occur in even the most mature and widely used applications. They disrupt user tasks, reduce trust, and highlight the need for consistent, thorough UI testing across devices, browsers, and screen sizes.

UI Functionality Bugs and Their Impact

UI functionality bugs occur when interface elements fail to perform their intended actions, even if they appear visually correct. Unlike purely visual glitches, these bugs directly prevent users from completing tasks, affecting core application processes and overall user satisfaction.

For example, a button may appear enabled but fail to trigger the corresponding function due to a JavaScript error or broken API integration. Similarly, a dropdown menu might display correctly but not update the selected value, preventing users from filtering or selecting options. Even small errors like these can accumulate, causing frustration and increasing support requests.

Forms are particularly prone to functionality bugs. Fields may reject valid input, reset unexpectedly, or fail to submit altogether. These issues disrupt critical processes such as account creation, form submissions, or e-commerce checkouts, often leading to task abandonment.

Navigation-related functionality bugs also have a significant impact. Broken links, unresponsive menus, or misbehaving modals can block access to important sections of a website. Users encountering these issues may perceive the application as unreliable, reducing trust and engagement.

The consequences of UI functionality bugs extend beyond user frustration. They can lead to lost revenue, diminished brand reputation, and increased operational costs due to higher support demands. Detecting and resolving these issues early in the development cycle is essential for delivering a seamless, dependable user experience.

How to Identify UI Bugs Early in Development

Detecting UI bugs early prevents them from escalating into major issues that affect user experience and increase development costs. Incorporating systematic checks during the development process helps catch both visual and functional issues before they reach production. Key strategies include:

• Implement Automated UI Testing: Use tools that simulate user interactions across browsers and devices. Automated tests can quickly detect broken buttons, misaligned elements, and layout inconsistencies, ensuring that new code does not introduce regressions.
• Perform Cross-Browser and Cross-Device Testing: Manually or automatically test your application on multiple browsers, operating systems, and screen sizes. Differences in rendering engines can cause subtle bugs that are otherwise easy to miss.
• Conduct Peer Reviews and UI Walkthroughs: Have developers and designers review interface changes in context. Observing UI flows from a fresh perspective often reveals usability issues and edge cases that automated tests might not catch.
• Use Prototyping and Wireframe Validation: Validate early-stage designs with interactive prototypes or wireframes. Identifying potential interaction issues at the design stage reduces the likelihood of introducing bugs during development.
• Monitor Real-Time Logs and Error Reports: Integrate logging for client-side errors, broken scripts, and failed API calls. Early detection through monitoring can uncover functional issues before they affect end-users.
• Leverage Beta Testing and User Feedback: Involve a controlled group of users to test the application in real-world scenarios. Early feedback can highlight UI bugs that were not detected during internal testing, especially those related to usability and accessibility.

By combining automated tools, manual reviews, and real-user testing, teams can identify UI bugs early, reduce the risk of major production issues, and improve overall application quality. 

To save time and enhance efficiency, teams can also use BrowserStack Bug Capture, a part of BrowserStack’s testing toolkit, to report bugs instantly with full context, screenshots, and device information, helping developers resolve issues faster.

Best Practices to Prevent UI Bugs in Future Development

Preventing UI bugs requires a combination of proactive design, rigorous testing, and continuous monitoring. Implementing structured practices early in development reduces the risk of errors and ensures a consistent, reliable user experience.

• Adopt a Component-Based Design System: Using reusable UI components with consistent styles, spacing, and behavior reduces the likelihood of alignment, font, or layout issues across the application.
• Enforce Code Reviews and Pair Programming: Regular peer reviews catch potential UI and functional bugs before code is merged. Pair programming encourages collaboration, reduces mistakes, and improves adherence to UI standards.
• Integrate Automated UI and Regression Testing: Automated tests help detect visual and functional regressions whenever new code is introduced, maintaining consistent behavior and appearance across releases.
• Conduct Regular Cross-Browser and Cross-Device Checks: Continuous testing on multiple browsers, devices, and screen resolutions ensures responsive layouts and prevents platform-specific bugs from reaching users.
• Focus on Accessibility from the Start: Incorporate ARIA attributes, semantic HTML, and keyboard navigation early in development. Testing for accessibility ensures that UI elements are usable by all users and prevents related bugs later.
• Document UI Guidelines and Patterns: Clear documentation of design patterns, style rules, and interaction standards helps maintain consistency and reduces errors when multiple developers work on the same project.

Conclusion

UI bugs can disrupt usability, frustrate users, and reduce trust in web applications. Identifying and addressing both visual and functional issues early in development is essential to maintain a seamless user experience, prevent task abandonment, and ensure consistent performance across devices and browsers.

Tools like BrowserStack Bug Capture, part of BrowserStack’s broader testing toolkit, make reporting and tracking UI bugs faster and more efficient. By capturing full context, screenshots, and device information, teams can streamline communication between testers and developers, accelerating bug resolution and enhancing the reliability of web applications.