Why Does Software Have Bugs?

One common question that plagues many Software Testers is “What causes software bugs?” and “How do these bugs come into existence?”. This guide strives to answer these queries in understandable language.

In this guide, we will delve into the top 20 reasons “why Bugs appear in Software”. 

What is a Software Bug?

A Software Bug refers to a glitch or aberration in a program leading to unexpected or incorrect results. It’s an error that stops the application from operating the way it’s expected to.

What Causes Bugs in Software?

There are numerous reasons for the emergence of Software Bugs. The most frequent cause is human errors in designing and coding software.

Once you understand what causes Software Defects, it will be easier to implement corrective measures to decrease these defects.

Top 20 Causes for Software Bugs

#1) Lack of or Poor Communication

The successful b of any software application relies upon the effective communication among stakeholders, development, and testing teams. Misunderstanding requirements and incorrect interpretation of requirements are two primary factors causing defects in software.

Additionally, defects may be injected at the developmental stage when the exact requirements are not properly communicated to the development teams.

#2) Complexity of Software

The intricacy of current software programs can be intimidating for those who are not experienced in contemporary software development.

Graphical User Interfaces, Client-Server and Distributed Applications, Data Communications, massive relational databases, and the sheer dimensions of applications have all led to an exponential upsurge in software/system complexity.

Use of object-oriented techniques can add to the complexity, rather than simplify, a project if not properly managed.

#3) Programming Errors

Programmers, not unlike anyone else, can make common programming mistakes. Not every developer is an expert in the field. Less experienced programmers or programmers without adequate domain knowledge can infuse simple errors while coding.

The lack of basic coding practices, unit testing, debugging are some of the common reasons why these issues are introduced during the development stage.

#4) Altering Requirements

The customer may fail to comprehend the repercussions of changes, or they might understand but still request changes; this can lead to rescheduling of engineers, impacts on other projects, already completed work might need to be tweaked or discarded, potential changes in hardware requirements, etc.

If there are any minor or major changes, unidentified and identified dependencies, then parts of the project are likely to clash and create problems, and the complexity of keeping track of alterations may lead to mistakes. The morale of the engineering staff may be affected.

In certain fast-paced business environments, continuous modification of requirements may be inevitable.

In these situations, management should understand the associated risks, and QA & test engineers must adapt and devise a plan for continuous thorough testing to prevent the unavoidable bugs from spiralling out of control.

#5) Time Constraints

Planning software projects is a difficult task, frequently involving a great deal of guesswork. When deadlines approach and workload mounts, mistakes are bound to occur.

Unrealistic schedules, although not common, pose a significant issue in small-scale projects/companies, resulting in software bugs. If there isn’t adequate time for appropriate design, coding, and testing, the introduction of defects becomes highly likely.

#6) Arrogant or Overconfident Individuals

People tend to say things like:

• ‘no problem’
• ‘piece of cake’
• ‘I can whip that out in a few hours’
• ‘It should be easy to update that old code’

Rather than:

• ‘That adds a lot of complexity and we may make a lot of mistakes’.
• ‘We have no idea if we can do that; we’ll wing it’.
• ‘I can’t estimate how long it will take until I take a closer look’.
• ‘We can’t figure out what that old spaghetti code did in the first place’.
• If there are too many unrealistic ‘no problem’s’, it results in software bugs.

#7) Insufficiently Documented C

Maintaining and modifying code that’s poorly written or insufficiently documented is challenging; the result is Software Bugs. In many firms, management doesn’t motivate programmers to document their code or write clear, easy-to-understand code.

In fact, the opposite is usually true: they are praised for quickly producing code, and there’s job security if no one else can understand it (‘if it was hard to write, it should be hard to read’).

Any new programmer working on this code might struggle due to the complexity of the project and the insufficiently documented code. It often takes longer to make even minor changes in poorly documented code, as there’s a huge learning curve before making any code modification.

#8) Tools Used in Software Development

Visual tools, class libraries, compilers, scripting tools, etc. often bring their own bugs or are poorly documented, contributing to added bugs.

Software programmers frequently use continuously changing software tools. Keeping up with the different versions and their compatibility is a significant ongoing concern.

=> Discover more about Software Development Tools

#9) Out-of-date Automation Scripts

Writing automation scripts is time-consuming, especially for complex scenarios. If the automation team drafts any test script and fails to update it over time, then that test might become outdated.

If the automation test does not properly validate the results, then it won’t be capable of identifying the defects.

#10) Shortage of Adept Testers

Having experienced testers with domain knowledge is extremely crucial for the success of any project. However, not all companies are able to hire only experienced testers.

Domain knowledge and the tester’s ability to identify defects can result in superior software. A compromise on any of this can lead to error-ridden software.

Here are a few more causes for Software Bugs. These causes largely apply for Software Testing Life Cycle:

#11) Not maintaining a proper test environment for testing all requirements.

#12) Coding or writing test cases without fully understanding the requirements.

#13) Incorrect design leading to issues in all stages of the Software Development Cycle.

#14) Frequently releasing software patches without completing the Software Testing Life Cycle.

#15) Not imparting training to resources on the skills required for properly developing or testing the application.

#16) Allowing little or no time for Regression Testing.

#17) Not Automating Repetitive Test Cases and relying on the testers for manual verification every time.

#18) Not prioritizing test execution.

#19) Failing to consistently monitor the progress of development and test execution. Eleventh-hour changes are susceptible to errors.

#20) Any wrong assumption made during coding and testing stages.

Conclusion

Several factors lead to the occurrence of software bugs. This guide lists the top 20 reasons with a straightforward explanation.

Do you think we’ve omitted any reason from the above list? Please share your thoughts in the comments section below.