Common Types of Bugs in Software Testing

January 2, 2024Kiruthika Devaraj
Common Types of Bugs in Software Testing

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Did you find a bug? I mean in the software! Software bugs can be the bane of any software project, causing delays, disruption, or even software failures. Any software development project must pay close attention to bug identification and resolution. This blog looks at some of the most common bugs in software testing processes. We’ll also explore how they can be identified and solved quickly and effectively so software projects can stay on track and meet their goals. 

By looking at these common bug types, we can better understand how to manage them and ensure that our software projects stay on course.

find a bug

Did you find a BUG?

What is a Software Bug?

Software bugs are errors, flaws, deficiencies, or defects in a computer program or system that cause it to produce an incorrect or unexpected result or to behave in unintended ways.

Different Types of Bugs in Software Testing:

Software bugs can be classified into multiple categories based on their nature and impact. Broadly speaking, these categories include Functional Bugs, Logical Bugs, Workflow Bugs, Unit Level Bugs, System-Level Integration Bugs, Out of Bound Bugs, and Security Bugs.

1. Functional Bugs

Functional bugs refer to defects or issues in software applications that affect their intended functionality. These bugs can manifest in various ways, such as incorrect calculations, unexpected behavior, crashes, or unresponsive features. They can arise due to coding errors, inadequate testing, compatibility issues, or external factors like hardware limitations.

For example, for functional testing, let us consider a scenario wherein the user logs into their Testsigma account. The Email field within the login page fails to accept special characters like “@” and “.”, , triggering a functional defect in the form of an error message.

Functional bug

2. Logical Bugs

Do you know Logical bugs are common in software development and can be quite challenging to identify and fix? Unlike syntax errors, which are relatively easy to spot due to their violation of the programming language’s rules, logical bugs occur when the code does not produce the expected output or behavior.

In the image shown below, the user’s action of clicking on the “Blog” page in Testsigma is depicted. It would be considered a logical bug if the user is redirected to the “Support” or any other page.

logical bug

3. Workflow Bugs

This bug can be a major hindrance to productivity and efficiency in any organization. These bugs refer to glitches, errors, or bottlenecks within a workflow process, causing team members delays, confusion, and frustration.

Let’s consider an example to explain this concept. Upon accessing the website – Testsigma.com on the below-mentioned page, the user is expected to be redirected to the documents page upon clicking the “Doc” icon. However, this expected behavior does not occur. In that case, it can be inferred that a workflow bug exists within the system.

workflow bug

4. Unit Level Bugs

Unit-level bugs refer to the defects or errors at the smallest testable component of a software system, known as a unit. These units can be functions, methods, classes, or modules. When developers write code, they break it into smaller units to make it more manageable and easier to test.

Explaining a unit-level bug through an example is a simple task. The image shows no action after clicking the “Schedule a Demo” button. Based on this observation, it can be concluded that the issue is a unit-level bug, which pertains to a defect that occurs at the smallest unit of code – a module, function, or statement.

Unit level bug

5. System-Level Integration Bugs

System-level integration bugs refer to the issues that arise when different components or subsystems of a complex system fail to work together seamlessly. These bugs can occur for various reasons, such as incompatible interfaces, module miscommunication, or inadequate testing.

Consider an example scenario –

Suppose we have a web application with multiple modules like user registration, login,  checkout and payment processing. Different teams develop each module, which must be integrated for the application to function correctly. The application throws an error when the user clicks on “Proceed to Payment” – means the system failed where the checkout was integrated with payment. This will be an example of a system-level integration bug.

system level integration bug

6. Out of Bound Bugs

Out Of Bound Bugs occur with logical and arithmetic errors exceeding the allowable boundaries of a specified operation.

Consider the following scenario in which a user attempts to schedule a Demo in Testsigma. Upon navigating to the TimeSlot page, the user incorrectly selects a date one day before the current date, July 18th, 2023. As a result, the Demo gets scheduled for July 17th, 2023, which is outside the acceptable range of dates. This can be categorized as an out-of-bounds bug.

Out of bound bug

7. Security Bugs

These are persistent and concerning issues in the world of technology. These bugs refer to vulnerabilities or flaws in software, hardware, or systems that malicious actors can exploit to gain unauthorized access, steal sensitive information, disrupt services, or cause other harmful consequences.

So, here is an example of a security flaw. Look at the image below where the user enters the wrong combination login on Testsigma login page, it lets the user in! This is a major software flaw because it exposes the site to security risks. This will enable anyone to log in to the application. It’s a security bug.

Security bugs

Common Examples of Software Bugs

Software bugs are flaws within a program that prevents it from performing correctly and can be caused by design or coding errors. Common examples of software bugs include: 

  • Unexpected program crashes
  • Results that don’t match expectations, 
  • The program encountering an infinite loop,
  • Incorrect calculations, 
  • Data missing from a database
  • Malfunctioning user interface elements,
  • Unresponsive API 
  • Security vulnerabilities 
  • Errors with file permissions 
  • Unnatural slowness 
  • Compatibility issues

Impact of Software Bugs!

Software bugs can have far-reaching consequences on software systems, businesses, and users alike. The following points outline the primary effects of software bugs:

1. Extended Development Time: Software bugs can lead to a prolonged development period, as they need to be found, identified, and corrected.

2. Increased Cost: Investigating and fixing software bugs can be expensive and time-consuming, increasing development costs.

3. Reduced System Quality: Bugs may prevent a software system from functioning properly, decreasing system quality.

4. User Frustration: Software bugs can create confusion, frustration, and dissatisfaction, leading to a poor user experience.

5. Regulatory Compliance Violations: Software bugs can sometimes cause a business to violate the applicable regulatory standards.

How to Find Underlying Software Bugs?

Finding underlying software bugs can be a daunting process for developers, but it can be done if it is done systematically. To find the underlying software bug, the following steps should be taken: 

  1. Begin bug-hunting via exploration of the features of the software: Test each feature and identify underperforming or unexpected behaviors; for example, within Testsigma Web Application, if we are testing the “login feature” – test the logging in/out process, and note any errors in the loading/saving/validation of data. 
  2. Carefully study the user interface: Explore every menu, every button, every page, etc., and look for inconsistencies and unexpected features. For example, within if we are testing the registration page for Testsigma application, you need to analyze the user interface for that page and ensure that all input fields are validated correctly. 
  3. Set up test plans: Set up user scenarios for various functions the software should have and thoroughly test each scenario. For example, when testing the registration process in Testsigma Web Application, create a plan to register a user, log out, log in back, and verify the login credentials are correct. 
  4. Make use of existing automation tools. Executing existing automation scripts and verifying if the executables are returning expected output can be immensely helpful in uncovering unknown software bugs. For these, you should use a test automation tool that goes well with your application.

    Testsigma is a test automation tool that lets you automate your tests for web, mobile, desktop and APIs, from the same place. It is a no-code test automation platform that makes it very easy to automate your tests in simple English.

Identify and Resolve Bugs!

Finding and fixing bugs can be annoying, and it takes time and effort to go through your code carefully. But it can also be pretty cool! You might even feel like a detective on the case.

Identifying and resolving bugs involves various steps, such as: 

1. Isolating the source of the bug. 

2. Running through the code and looking for possible errors. 

3. Make sure all parameters are correct and rerun the code. 

4. Refactoring the code to ensure optimal performance. 

5. Testing the code again to find any new potential bugs.


Bug testing is an essential part of the software development process and helps to ensure that software is properly tested prior to launch. Identifying and resolving bugs during development is important to deliver a successful and user-friendly product. With a better understanding of common bugs, developers can take preventive measures and improve software quality.

Frequently Asked Questions

What is the most common type of software bug?

The most common type of software bug is coding errors, which are found in the code written to make the software operational. These errors may lead to crashed systems, unexpected errors, or incorrect output.

What is the classification of a bug in testing?

Generally, bugs are classified as either major or minor, depending on their impact on the program. Major bugs should be prioritized and fixed immediately, while minor bugs may be addressed later.

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