What is the difference between an bug and error?

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  • Aug 2nd, 2005

Error: The difference between expected result and actual result is error 
Bug: If that error comes at the tome of development stage before production then it is bug. 
Defect: If that error comes after production then we say it is defect. 

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  • Oct 3rd, 2005

according u r answer what am i understanding, error means what exact output for our requirment that is not done due to some erros. and bugs are syntatical occcurs before devolping the product/software.

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Amit Kr. Gupta

  • Oct 12th, 2005

Needs information on Testing Software...

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  • Oct 17th, 2005

error is a variance from the actual and expected and bug is an error that comes during development.

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  • Nov 17th, 2005

Error: Is an undesirable deviation from requirements  or Cosmetic .

Bug: Is an error found BEFORE the application goes into production or missing Functionality.

Defect :Is an error found AFTER the application goes into production or missing Requirement





  • Feb 14th, 2006

Error: When we found any deviation from our required output in the developement environmet we call it as Error.Bug: when twe found deviation from our System Requirement Specification(SRS) in the testing environment then we call it as BUG.Defect: When some problem found in the production environment we call it as Defect.

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shahid hussain

  • Mar 7th, 2006

error : error resides in a program, error terminates the Execution of a program,

as tester he will testing the application,where application is the output of an program ,where program are set of instructions,tester find defects in application.defect means the diffrence between the expected & actual.

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  • Apr 22nd, 2006

Error: Deviation for actual and the expected/theoretical value.

Bug: An Error found in the development environment before the product is shipped to the customer.

Defect: An Error found in the product itself after it is shipped to the customer

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  • May 5th, 2006

hiError: The deviation occures in Code is known as Error.......It means it is at Developers Level Problem.Bug: The deviation between Expected Behaviour and Actual Behaviour is known as Bug.....It means it is at Tester Level Problem.Defect: The deviation in outcome product is known as Defect or The deviation in Tested application is Defect.....It means it is at Customer Level Proble..Error leads to Bug.........and Bug leads to Defect.........Is there any mistakes done please excuse........

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Dileep Kumar

  • Sep 21st, 2006

Hi all,Error : it's a mistake in programme. eg: when we compile a programme in C language there we can see the number of errors and warning. Bug: After coding and compiling we'll find the mismatch between expected and actual resultcheersdileepkumar.g@gmail.com


  • Sep 26th, 2006

Simply we can say Bug comes when the project is under development team whereas error comes when the product goes for validity testing or for certification. Two different technical terms were used in different places.

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  • Dec 28th, 2006

Error: any mistake in coding is called error.

Defect: That error is founded by test engineer then it is called as defect.

Bug: That defect is accepted by developer then we will call it as bug.

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  • Mar 18th, 2007

ERROR: It is nothing but the syntax errors or any mistakes in source code

BUG: While development of any software the errors are known as the BUG

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  • May 12th, 2007

Error : Human action that produce a fault occurs.

Bug : Issue is accepted by the developer.

Issue : Mistake in the application with the expected behaviour by testing (validation time) the application. The mistake is called issue.

Defect : If there is any mistake/problem in client environment application, the application is used by the customer, that problem/mistake is called defect.

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  • Jun 13th, 2007

Error: The difference between expected result and actual result is error?
Bug: Is a process flaw, which is induced in the design phase due to?misunderstanding of the RDD/RFS/SRS.

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  • Aug 18th, 2007

An error is a human action that produces incorrect result

Defect is a manifestation of an error in the software

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  • Apr 21st, 2008

Bug is the problem getting at the time of testing.

Error is a runtime event which cannot be handled & is found by users.

Defect is the problem getting on customers hand.

Exception is the unexpected runtime event, which is meant to be handled.

Exception is found by developers.
Bug is found by testers.
Error is found by users.

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  • Sep 3rd, 2009

Bug is a hidden error that was known after developed the software/program.

Error is mistake done at compile time, or running time.

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  • Sep 3rd, 2009

A bug is something that occurs against the requirements.
If the requirement says that an error msg should be displayed when the user enters alphabet instead of a number and the error msg does not show up, then it is a bug.

An error could be as per the requirements or due to some conflict in the system - It depends on the type of Error that you see.

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seema sharma

  • Jul 28th, 2011

Bug is when something works incorrectly & Error i when something doesn't work at all.

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  • Oct 14th, 2011

All the 3 terms are used interchangeably but do have fluid difference between them based on the context.

Bug is any unintended behavior, but the intended behavior is not set out in the requirements document.

Error usually pertains to syntax of the code, or arises from user input. Precisely error is anything that should be theoretically correct.

Defect is mismatch between actual result and requirement.

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  • Apr 20th, 2015

Error-which occurs at compile time

Bug-which occurs at run-time

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  • May 8th, 2015

Defect : Difference between expected result and actual result.
Bug : Error found in development environment before the product is shipped to customer.

Error : It is one which is generated cause of wrong login, syntax. Change functionality of program.

Difference between Defect & Failure : When defect reaches to customer called failure and if defect is detected internally & resolved called defect.

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  • Sep 19th, 2015

Error is syntax mistake. Bug means the code logic which deflects from the actual expected output

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Kalvan Kathiravan

  • May 27th, 2016

A mistake is an error caused by a fault.
An error is a term used to describe any issue that arises unexpectedly that cause a computer to not function properly.

A bug is a coding error in a computer program.
A software bug is an error, flaw, failure or fault in a computer program or system that causes it to produce an incorrect or unexpected result.

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  • Nov 23rd, 2016

Error:(When a mistake find in coding)/(Error comes in coding)
Bug:(When a mistake find in an application/software)/(Bug comes in an Application/Software)

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  • Jul 17th, 2017

Small deviation between actual and expected output.
It can rectify testers.

It can occur compile time.
It can rectify programmers

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  • Jun 19th, 2021

error is a mistake find in the program, a tester finds the error called as defect & and this type is accepted by the developer is called a bug.

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