Bugs in Software Testing: Types, Detection and Resolution

With billions of devices, browsers, and environments interacting at once, identifying and fixing defects has become a mission-critical priority. Automation tools like Testsigma help teams prevent regressions and maintain stability, making it vital to understand bug types, root causes, and effective detection methods.

What is a Bug in Software Testing?

A bug in software testing is any flaw, error, or unexpected behavior that causes software to function incorrectly, behave inconsistently, or deviate from expected results. 

In simple terms, a software bug is a defect that affects functionality, performance, usability, or reliability.

Why Do Bugs Occur?

Bugs arise from multiple root causes, including:

• Programming mistakes such as incorrect logic, syntax errors, or inaccurate algorithms.
• Misunderstood or incomplete requirements, leading the product to behave differently than intended.
• Integration issues when dependencies, APIs, or services interact incorrectly.
• Environmental inconsistencies – OS, browser, device, or network differences.
• Poor test coverage or missed scenarios, leading to defects surfacing late in development.
• Human errors during manual testing or during validation steps.

Impact of Bugs in Real-World Software Systems

The consequences of bugs extend far beyond minor inconvenience. Real-world failures show how defects can:

• Interrupt transactions or cause financial losses
• Expose sensitive data through security flaws
• Crash systems at scale
• Lead to user churn and negative brand perception
• Cause costly recalls and service disruptions

Industry studies show that fixing a bug in testing costs significantly less than fixing a software bug in production. Early detection, therefore, remains one of the highest ROI areas of modern QA.

Types of Bugs in Software Testing

Understanding the different types of bugs helps teams prioritize, classify, and fix issues faster. Below is a categorized breakdown enriched with examples and insights found across the uploaded blogs.

Functional Bugs

A functional bug occurs when a feature does not work the way it is supposed to according to the requirements or user expectations.

Example: Clicking the “Submit” button on a form does nothing, even though the form fields are correctly filled.

Logical Bugs

A logical bug appears when the software uses incorrect reasoning or flawed calculations, leading to wrong outputs even though the feature technically works.

Example: A discount offer of 10% is applied twice, reducing the price far below what it should be.

Workflow Bugs

A workflow bug breaks multi-step actions where the user needs to complete a sequence, causing the flow to stop midway.

Example: A user adds items to a cart, but at checkout, the “Proceed to Payment” button is disabled or throws an error.

Unit-Level Bugs

Bugs confined to a single function, method, or small component, usually caught during unit testing.

Example: A date-converter utility returns 2025-13-45 instead of a valid formatted date.

System-Level Integration Bugs

These bugs appear only when two or more modules interact, even though each module works fine independently.

Example: The payment gateway sends a success response, but the order processing system marks the transaction as failed due to schema mismatch.

Out-of-bound Bugs

These bugs occur when software receives inputs outside the allowed or expected limits.

Example: A textbox accepts only 50 characters, but entering 200 characters crashes the UI or causes layout overflow.

Security Bugs

Flaws that expose the system to unauthorized access, data leaks, or malicious manipulation.

Example: A login form that does not validate input, allowing SQL injection to bypass authentication.

Performance Bugs

These affect the speed, scalability, response time, or resource usage of an application.

Example: A dashboard takes more than 10 seconds to load when the number of records exceeds 10,000.

User Interface (Ui/ux) Bugs

Visual or usability issues that affect the layout, readability, accessibility, or interaction quality.

Example: Buttons overlap on mobile screens, making them impossible to tap.

Compatibility Bugs

Bugs that appear only on specific browsers, OS versions, device types, or screen sizes.

Example: A page works perfectly on Chrome but breaks on Safari due to unsupported CSS properties.

Content Bugs

Errors in the textual or media content, not in the functionality.

Example: A page shows “Your order is confirmed” or contains broken links.

Even with clear classifications, a few defects may go unnoticed. Explore practical ways to manage them in A Tester’s Guide to Deal with Missed Bugs.

Functional Vs. Logical Bugs

Functional and logical bugs often look similar on the surface, but they originate from completely different failure points in software behavior. 

Criteria	Functional Bug	Logical Bug
Definition	Occurs when a feature doesn’t work as required	Occurs when logic produces wrong outputs
Root Cause	Requirement mismatch, UI errors	Algorithmic or decision-making flaws
Example	Submit button not working	Discount calculation incorrect
Detectable Through	Functional testing	Unit testing, white-box testing
Severity	Often high	Can be critical depending on the feature

Real Examples of Common Bug Types

Real-world bugs rarely present themselves in isolation: they often break user flows, distort layouts, or quietly corrupt data. 

Here are three easy-to-understand examples that QA teams frequently encounter, along with how Testsigma helps uncover, capture, and troubleshoot them quickly.

1. Login Workflow Bug

A valid user can’t log in because the API throws a 500 error when the password contains special characters. Testsigma captures screenshots, API logs, and execution video for the failing step, making the root cause obvious.

Watch the bug-hunting demo for similar workflow issues.

2. UI Alignment Bug

On smaller screens, buttons overlap and block interactions. Testsigma’s cross-device testing shows the exact viewport where the UI breaks and highlights visual differences with screenshots.

3. DATA Handling Logic Bug

A report export misses entries due to incorrect filter logic. Testsigma’s data-driven testing and captured output files clearly show mismatched expected vs actual results.

Teams using Testsigma can visually record scenarios, generate screenshots, and replay failures step-by-step to diagnose these bugs quickly. 

How to Find Bugs in Software Testing

Defect tracking is critical. Both manual and automated approaches play complementary roles in uncovering issues during mobile testing and website testing.

Manual vs. Automated Testing Approaches:

Both methods uncover different bug types: using them together ensures wider coverage and fewer escaped defects.

Aspect	Manual Testing	Automated Testing
Strength	Creative insights and human intuition	Speed, repeatability, large coverage
Best For	Exploratory checks, UI feel, edge cases	Regression, compatibility, load, continuous testing
Limitations	Slow, inconsistent, not scalable	Needs setup, may miss UX nuances
Examples	Usability review, ad-hoc tests	CI-triggered regression suite, data-driven tests

Automation platforms like Testsigma ensure regressions don’t slip through, especially when performing repeated tests at scale.

How to Find Bugs in App Testing?

Mobile apps behave differently across devices, inputs, and network states – making focused bug-hunting essential.

Let’s look at a few ways to find bugs in app testing:

• Test on real devices to capture hardware-specific issues
• Validate gestures, permissions, and lifecycle transitions (background/foreground)
• Check offline, unstable, or low-network scenarios
• Test push notifications, deep links, and app routing
• Validate install/uninstall, version upgrades, and memory usage
• Stress test with rapid taps, swipes, and screen rotations

How to Find Bugs in Web Testing?

Websites break differently across browsers, layouts, and API interactions – so broad, environment-based testing is critical.

Let’s look at a few ways to find bugs in web testing:

• Test across browsers (Chrome, Firefox, Safari, Edge)
• Validate responsive design on different screen sizes
• Check forms, routing, and API responses
• Test security headers, SSL configuration, and caching
• Validate accessibility (contrast, keyboard navigation)
• Run load tests for slow pages or server-side issues

Exploratory Testing and Quick Attacks

Rapid bug discovery techniques include:

Technique	Focus	Benefit
Pareto Principle (80/20 Rule)	High-risk 20% areas	Faster early bug discovery
Real User Journeys	Signup → Login → Checkout → Logout	Catches workflow breaks
Boundary and Edge Cases	Max/empty inputs, special characters	Exposes edge-condition failures
Monkey Testing	Random actions	Reveals crashes or instability

Comprehensive Detection Methods

These approaches provide thorough detection for deeper and complex bugs:

• Regression testing for release stability
• Performance testing for load, stress, and endurance
• Compatibility testing across browsers & devices
• Accessibility testing for WCAG compliance
• Security testing to uncover injection, CSRF, and auth flaws
• Integration and API testing for module-to-module behavior

Debugging & Diagnosis Best Practices

To ensure efficient debugging:

• Capture clear logs, console output, and API responses
• Reproduce bugs consistently using step-by-step flows
• Analyze stack traces
• Use platform-specific debugging tools
• Automate logs and screenshots via Testsigma to speed RCA

Here’s a quick checklist for accurate bug fixing: 

• Verify the bug is reproducible
• Confirm expected vs. actual behavior
• Identify exact root cause (environment, data, logic, integration)
• Apply minimally invasive fixes
• Re-test related areas (impact analysis)
• Document resolution clearly

Download the complete bug-fixing checklist PDF to streamline debugging, reduce missed defects, and build a more reliable testing workflow.

If you are still wondering about how to write a good bug report, some tips can be procured from an elaborate checklist such as this. 

Handling and Preventing Missed OR Production Bugs

Even the best teams occasionally face bugs that slip into production, and managing them well is key to reducing impact and preventing recurrence. This starts with structured actions such as:

• Immediate triage to classify severity and user impact
• Rollback or hotfix to restore functionality quickly
• Feature flags to isolate faulty features without system-wide disruption
• Blue-green deployments to minimize downtime and risk
• Shift-right testing to observe real usage in safe environments

Once stability is restored, teams follow through with deeper root-cause work using techniques like the 5 Whys, Fishbone analysis, error-pattern analysis, and retrospectives after incident in software testing.

Together, these steps create a clear feedback loop that strengthens processes and reduces the chances of recurring bugs in software testing.

Building a Bug-Prevention Culture

Building a bug-prevention culture starts with recognizing that quality is a collective responsibility, supported by practices that keep issues from slipping through.

• Three Amigos meetings: Developers + testers + product align upfront
• Code reviews and pair programming reduce logic and workflow errors
• Bug bashes uncover edge cases through team-wide collaboration
• Automated quality gates enforce standards before merging

Prevention always beats detection, especially in high-velocity product teams.

Testsigma’s Edge in Bug Detection and Automation

Testsigma enables teams to detect, reproduce, and prevent bugs faster with:

• No-code test creation for rapid coverage expansion
• AI-powered automation that self-heals flaky tests
• Cross-browser and cross-device testing
• Cloud execution at scale
• CI/CD integration for continuous quality
• Real-time debugging with screenshots, logs, and video
• Reusable test steps across apps and platforms

Whether you’re building mobile, web, or API-driven products, Testsigma helps ensure fewer bugs escape to production and testing cycles remain efficient.

Why Early Bug Detection Shapes Better Releases

A strong understanding of what is a bug in software testing, the types of bugs, and effective detection methods enables teams to ship stable, user-friendly software at scale. 

Pairing these fundamentals with automation tools like Testsigma allows teams to catch issues earlier, test more thoroughly, and boost confidence in every release.

Try Testsigma for free and level up your bug detection today.