This tutorial discusses the top 20 reasons “Why Does Software Have Bugs”. Understand why do bugs and failures occur in software:
What is a Software Bug?
A Software Bug is a failure, flaw, or error in a program that causes undesired or incorrect results or behaves in an unintended way. It is an anomaly (error/unexpected behavior) that prevents the application from functioning as it was expected to.
Table of Contents:
Why Does Software Have Bugs
Why software has defects is a very broad question and at times can be purely technical. There are many reasons for the occurrence of Software Bugs. Some people that are not so tech-savvy call them computer bugs.
The most common reasons are human errors and mistakes made in designing the program and writing the source code. Another prominent reason could be incorrect interpretation while getting the software requirements.
Once you get to know why the software is having defects, and the causes for bugs, then it will be easier to take corrective actions to resolve and minimize these defects.
Top 20 Reasons for Software Bugs
Let us understand in detail.
#1) Miscommunication or No Communication
The success of any software application depends on the organized communication between stakeholders, development, and testing teams, during various stages of the software development process. A lack of organized communication often leads to miscommunication.
Proper communication should start right from the time of requirement gathering, then its translation/interpretation to the document and continue during SDLC.
If the requirements remain unclear and incorrectly translated into specifications, the software is bound to have defects due to ambiguity in requirements. Certain Software Defects get introduced into the development stage itself if the developers are unaware of the right specifications.
Also, communication errors can happen if the software application is developed by some ‘X’ developer and maintained/modified by some other ‘Y’ developer.
Example: The development team deploys a new change but the testing team is unaware of it. Testers might suddenly find some unintended behavior and a lot of time can go into finding the cause. Proper communication within the team could have avoided this problem. So, effective communication remains the key to software development.
Also read =>
- Statistics on why Effective Communication is important in the Workplace.
- The 14 Most Common Communication Challenges
- Lack of Communication – How to Improve
#2) Software Complexity
The challenging complexity of the current software applications can be difficult to adapt to for anyone with little experience in modern-day, almost daily changing software development methods and techniques.
The enormous rise of various third-party libraries, Windows-type interfaces, Client-Server, and Distributed Applications, Data Communication Systems, large relational databases as well as free RDBMS, varied techniques for building APIs, a large number of development IDEs, and the sheer size of applications have all contributed to the exponential growth in software/system complexity.
Unless the project/program is well designed, using object-oriented techniques can complicate the entire program, instead of simplifying it.
Example: Assuming, in a program there are too many nested if-else statements and unfortunately in user interaction one of the logical paths gets triggered which was unintentionally missed in testing although rigorous testing was done.
This might very well lead to a software bug and debugging & fixing it could be a real nightmare. This cyclomatic complexity can be reduced using switch cases or ternary operators, as applicable.
#3) Lack of Designing Experience/Faulty Design Logic
As the design is the very core of SDLC, quite a good amount of brainstorming and R&D is required to arrive at a reliable and scalable design solution.
But, many times self-imposed timeline pressures, lack of patience, improper knowledge of technical aspects, and a lack of understanding of technical feasibility can all lead to faulty design and architecture which in turn will introduce several software defects at various levels of SDLC, resulting in extra cost and time.
Example: The popular communication app ‘Slack’ had received criticism for its public DM feature. Although a useful feature, allowing users (friends) from outside the organization to participate in chat was unacceptable to many organizations. Perhaps the Slack development team could have given more thought while designing this feature.
#4) Coding/Programming Errors
Programmers, like anyone else, can make common programming mistakes and may use ineffective coding techniques. This may involve poor coding practices like no code review, no unit testing, no debugging, unhandled errors, faulty input validations, and missing exception handling.
Along with these, if the developers use the wrong tools, for instance, faulty compilers, validators, debuggers, performance checking tools, etc., then there is a very high probability that lots of bugs will creep up in the application.
Also, not all developers are domain experts. Inexperienced programmers or developers without proper domain knowledge can introduce simple mistakes while coding.
Example: Clicking on the ‘Cancel’ button does not close the window (which was expected behavior), although entered values are not saved. This is one of the simplest and most often found bugs.
#5) Ever-Changing Requirements
[image source]
Continuously changing requirements may be a reality and fact of life in some fast-changing business environments and market needs. The motivation and enthusiasm of the development team may be certainly affected, and the quality of work may be reduced significantly.
Various known and unknown dependencies need to be taken care of while working on many such minor or major changes. A significant amount of QA effort may be required and if not done properly may bring in many bugs in software. Keeping track of all such changes is again an overhead and complex task, which may further result in more application errors
In such cases, the management must understand and evaluate the resulting risks, and QA & test engineers must adapt and plan for continuous extensive testing to keep the inevitable bugs from running out of control. All these will require much more time than the originally estimated time effort.
Example: For an e-commerce website, the initial requirement was for product search to be based on product name, but a few days before the release, it was decided to have a search based on product code as well. In this case, improper testing or insufficient testing time will almost certainly result in bugs getting leaked into the production environment.
Also, read => Continuous Changing Requirements – How to keep up
#6) Time Pressures (Unrealistic Time Schedule)
As we all know, scheduling time and effort for a software project is a difficult and complex task, often requiring a lot of guesswork and historical data. When deadlines loom and the pressure mounts, mistakes will happen. There could be bugs in coding – some or many.
Unrealistic schedules, though not common, are a major concern in small-scale projects/companies resulting in software bugs.
As a result of unrealistic release schedules, and project deadlines (internal/external), software developers may have to compromise on certain coding practices (no proper analysis, no proper design, less unit testing, etc.), which can increase the probability of bugs in software.
If there is not enough time for proper testing, it’s quite obvious that defects will leak. Last-minute feature/design changes can also introduce bugs, at times most dangerous software bugs.
[image source]
Example: Drag and book a resource (event) functionality (which was a high priority was developed for a multi-storefront application under a tight deadline. However, due to limited testing time, there were DST issues.
#7) Egotistical or Overconfident People
People prefer 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’
Instead of:
- ‘That adds a lot of complexity and we could end up making a lot of mistakes’.
- ‘We do not know if we can do that; we’ll wing it’.
- ‘I can’t estimate how long it will take until I take a closer look at it’.
- ‘We can’t figure out what that old spaghetti code did in the first place’.
- If there are too many unrealistic ‘no problems’, then it results in software bugs.
Making assumptions by being overconfident will certainly bring in some or many software bugs at each stage of SDLC.
Example: One of the developers was quite sure of taking care of the performance aspect while downloading a large chunk of data in MS Excel and suggested the tester not to carry out more tests with such data. Eventually, it resulted in a bug in the production environment.
#8) Poorly Documented Code
It is tough to maintain and modify code that is badly written or poorly documented; the result is Software Bugs. In many organizations, management provides no real incentive for programmers to document their code or write clear, understandable code. Many times there are no set processes and standards for coding.
In fact, it is usually the opposite, they get points mostly for quickly turning out code, and there’s job security if nobody else can understand it (‘if it was hard to write, it should be hard to read’).
This poorly written and not so well documented code becomes a maintenance nightmare. Any new programmer working on this code may get confused because of the complexity of the project and the poorly documented code.
Many times it takes a longer time to make even slight changes in poorly documented code, as there is a huge learning curve before making any code change.
Example: The testing team discovered several bugs as a result of the migration of some screens of a legacy product (which has been in use for over 20 years) from C++ to C#. The main reason was a lack of proper code documentation and/or comments.
Also Read => Importance of Documentation
#9) Software Development Tools (Third-party Tools and Libraries)
Visual tools, class libraries, shared DLLs, plug-ins, npm libraries, compilers, HTML editors, scripting tools, etc. often introduce their own bugs or are poorly documented, resulting in added bugs.
Software engineers tend to use continuously and rapidly changing/upgrading software tools. Keeping pace with the different versions and their compatibility is a real and major ongoing issue.
Example: Defects in Visual Studio Code or deprecated Python libraries add their own level of disadvantages/challenges to writing effective software.
=> Read more on Software Development Tools
#10) Obsolete Automation Scripts or Over-Reliance on Automation
The initial time and effort taken to write automation scripts are quite high, especially for complex scenarios. If manual test cases are not in proper shape, then the time required will significantly increase.
Automation scripts need to be maintained regularly, wherever required, as per the changes done in the application. If the changes are not done on time then those automation scripts can become obsolete.
Also, if the automation test script is not validating the right expected outcome, then it will not be able to catch the defects and it does not make any sense to rely on these scripts.
Being excessively reliant on automation testing can cause manual testers to miss bug(s). For successful automation testing experienced and dedicated personnel is required. Also, the support of management is of utmost importance.
Example: After the product enhancement, one of the automation test scripts was not updated in time. Furthermore, bugs were discovered late in the testing cycle because the corresponding manual test cases were not executed due to the presence of the automated script. This added to the delay in software delivery.
#11) Lack of Skilled Testers
Having skilled testers with domain knowledge is extremely important for the success of any project. Domain knowledge and the tester’s ability to find defects can produce high-quality software. But appointing all experienced testers is hardly possible for all companies as the cost factor and team dynamics come into the picture.
Compromise on any of this can result in buggy software.
Poor and insufficient testing is becoming the new norm or standard in many software companies. Testing is being taken lightly which may involve a lack of proper or no test cases, flaws in the testing process, and the process itself getting done without giving much importance. All of these factors can certainly cause various types of software bugs.
Example: One good example could be insufficient DST-related testing for the event booking software feature.
#12) Absence or Inadequate Version Control Mechanism
The development team can easily keep track of all the changes done to a code base with the use of proper version control tools/mechanisms. Lots of software errors definitely will be observed without having any version control of the code base.
Even while using version control, the developer should take care to ensure that he/she is having the latest version of the code before committing any changes to the relevant code file.
Example: If the developer commits changes to more than one task at once (which is not standard practice), reverting the code to the previous version (which may be required if the latest commit causes build issues, etc.) will be extremely difficult. As a result, new bugs may be introduced during the development phase.
#13) Frequent Releases
Releasing software versions (for example, patches) frequently may not allow the QA to go through the complete regression test cycle. This is one of the major reasons nowadays for having bugs in the production environment.
Example: The PDF download feature of a multi-storefront application began breaking in the production environment because the tester neglected testing of this feature due to insufficient time and the fact that it was only checked in the previous release, and no changes were made to this feature.
#14) Insufficient Training for Staff
Even for experienced staff some training may be required. Without sufficient training on required skills developers can write incorrect logic and testers may design not-so-accurate test cases, resulting in software bugs and errors at various stages of the SDLC and testing life cycle.
This may also involve misinterpretation of the gathered requirements/specifications.
Example: A survey application was collecting data, which could be downloaded as an MS Excel file. However, due to a lack of technical knowledge, the developer failed to consider performance issues that could arise as a result of a large amount of data.
When the record count reached 5000, the application began to hang for hours with no result. This test was also missed by the tester, most likely due to insufficient training.
#15) Changes at the Eleventh Hour (Last-Minute Changes)
Any changes done at the last minute either in the code or any dependencies (e.g. hardware requirement, version of libraries used) can cause the most dangerous software bugs and failures.
Example: The version of a third-party library in one of the web applications was changed just two days before the release. The tester clearly did not have enough time to test, and there was defect leakage into the production environment.
#16) Ineffective Testing Life Cycle
- Test cases are written without a proper understanding of requirements.
- No proper test setup (test environment) for different environments.
- Lack of traceability matrix
- Insufficient time is given for regression testing
- Lack of proper bug report
- Incorrect or missing test execution prioritization
- No importance is given to the testing process.
Here are a few more reasons for Software Bugs. These reasons mostly apply to Software Testing Life Cycle:
#17) Not Automating Repetitive Test Cases and depending on the testers for manual verification every time.
#18) Not tracking the development and test execution progress continuously.
#19) The incorrect design leads to issues being carried out in all phases of the Software Development Cycle.
#20) Any wrong assumption(s) made during coding and testing stages.
Conclusion
There are several reasons for the occurrence of software bugs. A list of the top 20 reasons was mentioned in this tutorial with a basic explanation. We hope you identified with a few or maybe many of the items we listed.
Please share your thoughts in the comments section below and do mention any other reasons you are aware of.
Thank u.
threerock.com, there u can find details about bugbase
hi,this is sandhya
recently i completed my training in testing at vizag.
the quieries asked in this site is being very useful to clarify our doubts regarding testing concepts.
Hi jk, it means it only stores the bugs we have tracked and for purely communication purpose and to safely store details in server.Right!!!!!!!!
Please any one give me more details about Bugbase.
Becoz i want to work on that automation tool.
Thanks,
Haripriya.
Hiii
I m Dhanashree.. i m Comm graduate. and had completed Software Testing Course in jan2009 from COEP Coll. pune.. but till the date I didnt get job. so please anybody know about vacancies for tester in Pune. please inform me..
Thank You
Thanks for help!
call : +91-9830704327
mail me: bishalchaperia@gmail.com
my email id::
murali.nair3188@gmail.com
Hello Maheswari,
Donot loose hope or confidence. First thing what the managers see is that whether ur CONFIDENT or not. And now the market is RISING UP, so, it is time for u to get ajob also. If u want any help ormore suggestions, i am ready to help u. ofcourse i am in this field for almost 6+ yrs and working in MNC’s: santoshpalvai@yahoo.com, Best of luck for ur future
hi
i have a doubt
What is the difference between Bug and Defect
Bug tracking tool that you use… is nothing but bugbase
Well done
hi
i have a doubt
What is the difference between Bug and Defect
Thanks in advance
Hi friends
In India which is the commonly used testing tool used and how much it covers the market share
pl help
hi
i m shweta . i m completed B.E.(I.T.). i m intrested in software testing so i m doing software testing course….
if there are vacancies/opening for software tester plz plz …
inform me on email id….
hi
Can i know wht r the limitations to testing ,
and
can i get notes related to silk testing
Thanks in advance
bye
Hi Friends,
Currently i am working in Non-IT field and planned to switch my career to testing.I had learned the basics of testing,and now i am very eager to learn testing practically with real time projects.
If any one interested to teach testing personally with real time projects , i will be more grateful, or else show me the right place in chennai.
Thanks & regards
selvam.ba@rediffmail.com
thnq for briefing me abt rapid test script wizard
Prajaktha i sincerely advice one thing as you are from commerce background i recommend you to go to finance side it is very difficult to survive in IT field according to the present situations so if possible learn acountiting packages and go in that direction. I know every one now a days looing farwrd to become a test engineer but it is very difficult. If you think that you that capability to go a head in this competition means i really wish u all the best for your commitement
If you are hyderabad means u can take coaching from
MIND Q or NAGESWARARAO both are in S.R NAGAR.
course duration is 45 days and fee structure is 4000
you should learn SQL SEVER also.
any way all the best for your career.
keep in touch and all the best once again.
hi…..
How do you differentiate between client and server? Which tool do you use to detect any error in client server configuration?
thanks girish.
Hi seema,
you did not mention your qualification. One thing i want to mention you seema that your are free with doing any job all these 4 years.
To start a career as test engineer you have to make that 4 years as you worked some where untill unless you keep experience it is impossible to get a job.If you want to keep experience means u should be technically sound in Manual testing, tools like QTP AND LOAD RUNNER, and more over you should have good command over UNIX, SQL SERVER and ORACLE. I am not frightening you this is the basic fact you should know. To get command over this it takes not less than 1 year so once think upon this if you are really want to get into IT job then reoly me again i will give you the details.
keep in touch
Hi All Commerce graduate,
Guy who r commerce graduate, n who having interest in Testing. They have got advantage in Bank and Finance domain projects.. So eventhough they are not from IT..they got chance in Testing as well…;)
Do well Guys,
Regards,
Yogendra
STH is a very good site for testers. I have 9 years experience in testing and I refer this site. I am based in hyderabad and want to share ideas on testing. My email-id is swami.prakash3@gmail.com. Thanks.
These are the few possible reasons for a software build to have bugs.
1) When the product launch date is nearing, the developer skips one or two minor bugs and provides the software build to the testing team.
2) When the developer misses out a bug by mistake and without checking the fixes, provides the software build to the testing team.
3) Once the developer fixes the bug and does not check any other functionality of the software which has been changed or modified due to the fixation of the new bug and provides the software build to the testing team.
hi
Thank u,
Hi Devi,
RapidTest Script Wizard, which is used in WinRunner, learns the application graphical user interface (which is abbreviated as GUI). It automatically creates a full suite of basic tests. The requirement of testers to create tests one at a time is reduced considerably. This is because the RapidTest Script Wizard walks through the application itself and reverse-engineers the test scripts directly from the application.
The RapidTest Script Wizard learns all the objects or windows which are present in the application. The RapidTest Script Wizard basically performs two tasks. The first task which the RapidTest Script Wizard performs is it systematically opens the windows in your application and learns the description of every GUI object. The wizard then stores the information in a GUI Map file. The second task which the RapidTest Script Wizard performs is it automatically gene rates tests which are based on the information which it learns as it navigates through the application.
hi
actually i’m working on manual testing in delhi from last 1.3 years…i’ve done testing certification als0
Now i want to switch to pune…
if u guys hav any info about any opening in pune(in testing) plz let me know
thanks
Ya absolutely hari!
hi
I am Commerce Graduate. i am intersted in software testing. i complete my graduation in 2005. can i do this course. right now i am working in SAP as Account Assistant in MUMBAI. is it possible for me to make careere in this?
Please guide me. it is possible for comm graguate to make career in this field. Can u tell me the duration, fees, institution or other best or required thing which i dnt know. plz guide me for this
Thanks
Hi Devi,
Very nice 2 here tat ur very interested in testng!
Try with hope u will get. Pls mention all ur skils in ur cv. ok. all the best devi. pls forward to me i will do my best ok
Hi
I am working as a techsupport executive in brigade i want a change in my career now days i am hearing more about testing tools that it has god opurtunities in that field i am a bsc graduate 2006 passed out so could you please suggest me what to do and please give the detail information about testing tools and where to learn and how to crack job, I am desperately in need of job as i am going to quit my current job………
could you please e-mail me in detail about testing and how to crack job in short span of time.
my E-mail ID: vamsi.kalepu@gmail.com
Please help me to build my career as a test engineer
i m working as requirement analyist in mumbai actually i confused how i work,
Hi, I know its a stupid question but is software error the same as bugs?
Thanks in advance
any information plz tell me my id satyamurthyd@gmail.com this is murthy
i am working in telecom domain(OMCR) for past one year,but interested in testing how can i switch my field,but i have done a course in manual and automation testing..
wat should i supposed to be done to get the job. i am B.E(ece) 2008 passed out…
hi
from last four years i am working as a housewife. although a post graduate in computer science ,from hyd. I want a break in the software testing at hyderabad .how shall i get this opportunity. Moreover how shall i get acquaintence about the software testing in detail ,please mail me and guide .
thanks
Hi,
Best of Luck, but becareful, plz donot put fake, if u put Fake experience also, try to maintain or else u will be def kicked…All the Best..
hi
Can i know wht r the limitations to testing ,
and
can i get notes related to silk testing
Thanks in advance
hi,
frnds many ask about testing oppotunities, first you people need to learn manual testing, after that prepare ur resume with effective nature about manual testing…….then search for jobs in internet …..any more about manual or automation leave a comment………
Hi Folks,
Pls anyone can tell the ans for this question..
What is Bugbase?
thnx in advance
Hi,
iam maheshwari.i completed MCA.after that i wasted my time bcs i dont have proper guidance to do job.also iam poor in english.from two years onwords iam searching on testing tools even i didnt get job still now.i attended so many interviews after 4 rounds also i rejected.like this i rejected everywhere.now iam in depretion.i dont know when will i get job.pls give me any suggestions .icant leave this bca i paid 1lakh thatsy.
hi santosh this is inayath bbm graduate completed in 2008 and currently working in bpo for almost 1.6 yrs interested in testing but does not know anything about is it good to enter in to this field suggest me pls. And after completion of the course can i get job and which is the best institute in bangalore which provides placement and good training.
hi
I am Commerce Graduate. i am intersted in IT. i complete my graduation in this year. can i do this course. right now i am doing C and C++ languege. is it possible or useful for me to make careere in this?
right now i am working but it is some how related to IT as well as SAP. Please guide me. it is possible for comm graguate to make career in this field. i am in BPO section Backoffice. can u tell me the duration, fees, institution or other best or required thing which i dnt know. plz guide me for this
Thanxs
hie guyz..murlee here..right now am working with reliance BPO as a CSR(techSupport)..completed my 6mnths there…but am not intrested in this field..am not made for serving customers..i am a Bsc (IT) student..appearing for my last sem this April-2010…want a career in SoftwareTesting..pls guide me how to achieve it..after graduation am planning to do PG in MCA..but donno whther i will break the MHT-CET..pls tell me everything on how to get this done..what shld i posses for the same..wht is the limit of the course..is it Worth doing..
hi
I want to get into this testing tools field, as i’m very passionate abt learning this, i’m learning testing tools from orbit, and also i’m completly from commerce background .I think that my keen passionate interest makes me survive in this field.
But i want to know wht would be the scope for a fresher , which org’s r using this ,pls let me know the list of the org using it.
sir
Plz tell me any one my decision right or worng
this is murthy i have 3 years exp in financial sector. i am mba holder. i am interested to learn testing is it correct decision. plz suggest witch inst is better in hyd?
Thanks for the valuable information
hi….
How did you prepare a test case for Software Testing? What do you do if even after your software testing process an error is found
saw ur answers regarding testing tools i am appreciate a lot , can u help me out .
Right now i am in australia pursuing diploma in computer field but not related to PR so i am deciding to comeback to india (some family problem) and do some course in testing tools what u think , i have some knowledge about computers i have done Bsc (2005) after that i am not taken any interested in doing job in india wasting my precious time by going abroad. I am 29 now i am sorry what i have done. Can u please suggest me that its good to do testing tools on this age.But i know that its difficult for me to go form the scratch but i can do, if u suggest good reply for my future.
By reading all this u get the idea what guy i was,from the bottome of my heart i am very regret what i have done, Now i am realised that how important the career is please please suggest me what to do , i am interest in computers field.
Thanks for ur preciuse by reading this.
One important think my english also not so good .
Hi Devi, pls do forward ur cv . And tell me if there are any openings if u know?
thanks in davance devi
Hi Sandhya,
Nice seeing ur comments. Yes it is helpful. If you have any doubts with respect to testing, you can contact me at santoshpalvai@yahoo.com.
Me working on tetsing from past6 yrs..
Defect: When an error found by the test engineer (testing department) then it is called defect Or Defect is nothing but deviation from the requirement.
Bug: if the defect is agreed by the developer then it converts into bug, which has to fix by the developer or post pond to next version. If am wrong pls let me know…..
Thnx
AnyComputer Program contains a bug no matter how well it is programmed.
The important here is that the program is run on processor which work is based on arithemetics. Hence Godel Theorem can be used.
So, this means all computer programming is Sisyphus work.
Hi JK
Read this,
BugBase–>A high quality software defect tracking tool. Very scalable so it’s useful for both small and large organisations. Highly configurable, integration with email, web based reporting etc.
Regards
GK
I am a new software tester. could you please give me some example or documents link to learn about this.
How can i get the proper document to write Test Script, Test Plan properly.
thanks in advance
HI JK
Surely let u know. giv ur id so that i can forward the mails regarding opening
Can any help me out , wht is rapid test scrip wizard, why it is used in teting tools
thank u jk
Rapid test script wizard
Nice article to understand about bugs in softwares. People can understand how bugs are inserted into softwares and how they can be found. If one knows how bugs can be inserted in software, finding them becomes easy…
Thanq very munch Mr.jaykay
This question is eating my brain from so many days
thanks alot 🙂
Dear anadan,
When bug get fails, that mean it again assign to developer to resolve it…;)
Regards,
Yogendra
Hi
I amworking in a leading bpo,these days i hear much about software testing career.can anybody help me in knowing how better it is to take this career………..
hai,
I have 2+ year experence for client site(NIC-National informatic center) in chennai. my nature of work: application maintaince and train to all staffs…
so now i’m looking for s/w testing…so how to prepare the testing interview and…. how to mention my experence..
so how to prepare my CV… Give me idea……….
hi….
What do you do (with the project staff) when the schedule fails
Hi,
i am completed BE electronics in june 2012. i have doute. can anyone tell me which option is peferable for me – software testing OR pgdwimc(cdac cours). i got 70% marks in final year.
Plz..I m working as a quality test engineer (6+ months), I really appreciate if you provide us the details of how to get this testing certifications done.
Hi,
Am an Engineer graduate(B.Tech IT), two years before i was working as a software engineer in an MNC, now i have become an housewife and now i would like to work from home. please let me know the process like how to start this job, kindly cntact me in 9841953176.
hi everyone, am working as test engineer.can anyone give me solution for testing latitude and longitude text boxes. there is no validation provided by the developers.