Bug Examples: Common Software Bugs Explained

What is a Software Bug?

A software bug is a mistake, flaw, or unintended behavior in a program that prevents it from performing correctly. Bugs can exist in any part of a system, including the user interface, backend logic, calculations, or integration with other systems. They often result in unexpected outputs, errors, or crashes that disrupt the user experience or affect business operations.

For example, a mobile banking app might calculate the wrong interest due to a programming error, or a website might freeze when a user submits a form. Bugs are essentially any deviation from the software’s intended functionality and can appear in simple apps or complex enterprise systems.

Common Examples of Software Bugs

Below is a detailed look at common bug types and how they can manifest in real-world software:

• Functional Bugs: Occur when a feature does not behave as expected. For example, a login button that fails for valid credentials or a “submit” action that does not save form data.
• Crash Bugs: Cause the software to stop working completely, often due to unhandled exceptions or memory errors. For instance, a mobile app might crash when opening a large image file.
• Logic Bugs: Happen when the program’s decision-making produces incorrect results. For example, a shopping cart applying discounts incorrectly due to flawed conditions in the code.
• Syntax Bugs: Arise from mistakes in the programming language’s rules, preventing the code from compiling or running. For instance, missing semicolons or misspelled keywords can stop the program entirely.
• Calculation Bugs: Lead to wrong numerical outputs, such as miscalculating totals in a billing system or incorrectly converting currency values.
• Control Flow Bugs: Occur when the sequence of execution leads to unexpected behavior, like a loop that skips necessary steps or a condition that never triggers.
• Performance Bugs: Cause software to run slowly, freeze, or consume excessive resources. For example, a page that loads in 30 seconds instead of a few seconds due to inefficient database queries.

Real-World Bug Examples

Software bugs directly affect products people use every day. Here are some real-world examples that illustrate their impact:

• Therac-25 Radiation Machine: A logic bug in this medical device caused massive overdoses of radiation because safety checks were skipped under certain conditions. This bug had fatal consequences, showing how critical software correctness can be.
• Knight Capital Group Trading Glitch: A syntax and control flow bug in trading algorithms led to the company losing $440 million in 45 minutes. Incorrect routing and execution of trades highlighted the dangers of overlooked code errors.
• Apple “goto fail” SSL Bug: A duplicated line in Apple’s SSL verification code created a critical security vulnerability, allowing attackers to bypass encryption and compromise user data.
• Mars Climate Orbiter: A calculation bug due to mismatched metric and imperial units caused the spacecraft to crash into Mars, showing how small errors in calculations can result in major failures.
• Instagram Outages: Performance bugs such as memory leaks or inefficient database queries caused temporary outages, leaving millions of users unable to access the app.

These examples show that software bugs can affect usability, security, finances, and human safety, making their identification and resolution a top priority in development.

How to Identify a Bug

Finding a bug requires careful observation, testing, and analysis. Bugs often appear when software behaves differently from expectations, produces errors, or crashes under certain conditions.

• Reproduce the Issue: Attempt to repeat the steps that cause the problem. For example, clicking a form submission button multiple times to see if it consistently fails helps confirm a functional bug.
• Check Error Messages and Logs: Review system logs, console outputs, or error messages. They often point to the source of the problem, such as syntax errors, failed database queries, or exceptions.
• Compare Expected vs Actual Behavior: Test the software against its requirements or specifications. For instance, if a discount calculation in an e-commerce app gives unexpected totals, it signals a calculation or logic bug.
• Boundary Testing: Test edge cases or unusual inputs. Entering extreme values, empty fields, or special characters can reveal control flow or crash bugs.
• Performance Monitoring: Measure load times, memory usage, and CPU consumption. Slow responses or resource spikes may indicate performance bugs.
• Cross-Platform Testing: Run the software across different devices, browsers, or operating systems. Bugs that appear only in certain environments often reveal compatibility issues.

After identifying issues through these steps, using a tool like BrowserStack Bug Capture can make reporting faster and more precise by automatically collecting screen activity, logs, and environment details, giving developers everything they need to reproduce and fix the bug quickly.

Conclusion

Software bugs can appear in many forms, from functional errors to performance slowdowns, and they directly affect user experience, business operations, and product quality. Recognizing the types of bugs and using systematic testing methods helps teams identify issues early and address them efficiently.

BrowserStack provides a streamlined way to capture, report, and share bugs with full context, including screen activity, logs, and environment details, making it faster for developers to reproduce and resolve issues.