I was asked following question -

There is a form on a web page and it has UI validation, but UI validation fails on QA environment and you log a bug for it. But developer cannot reproduce it on his environment. What could be possible reasons of developer not able to reproduce on his environment?

I had following answers -

  1. QA environment could have different build installed than what developer environment has.
  2. Browser version could be different what QA and Dev checked up
  3. Browser itself could be different what QA and Dev checked up

Could you please suggest if above are correct and what could be other possible reasons?

  • 2
    Browser cache could also be a factor here, especially when you are testing immediately after a new build.
    – Janaaaa
    Oct 21, 2017 at 20:24

4 Answers 4


Let me add my options

  1. There are some addons installed or not installed in DEV/QA browser

  2. There are networking or routing specific which makes client calls from DEV go to different resources (e.g. hosts file configuration) and that could impact if your UI is built with the help of Ajax requests

  3. There are different locale settings or time settings on client machine

  4. There are different screen resolutions which might break the layout of your UI

  5. Your browsers work in different modes.

  6. You have not specified the preconditions quite accurately so that you both start from different system states when you reproduce an issue.

  • 2
    I would also add that the developer may read your reproduction steps differently to what you intended. Easiest thing is to go to that developers environment and repro it yourself if possible.
    – K-8
    Oct 12, 2017 at 17:57

There is also option in defect tracking tools for comments by developers. When developer rejects some defect on defect tracking tool, he also mention his or her comments there. You can read that for the reason of rejecting. Then you can personally discuss with the developer.

Often it happens that a defect coming on your pc does not happen in developer pcs. It is said as defect has not REPRODUCED on developer pc. Tester should first check this on his own machine that whether is coming or not. Then tester job is then to try to reproduce it on the developer pc.

There may be several reasons due to which defect is not reproduced on developer pc. Few of them mentioned below(mostly related to web applications):

  1. Check the configuration of your application whether it is same on your pc and developer pc. For example there may be some configuration parameter in your application which you are testing that may not be set same in developer pc as it is on your testing environment.

  2. Check the configuration of browsers on which you are testing your application if it is web application. For example in IE often this issue raised due to the different document modes(by pressing f12 in IE).

    Another example of this is compatible modes setting on developer and tester browsers should be same.

  3. Screen layout defects can be rejected due to different screen resolutions on tester and developer machines.

  4. Often just cleaning the cache of browsers of developer machine sometimes reproduced the defect.

  5. Often it happens that developer has tested it on desktop while tester has tested it on laptops.

  6. Often it happens that tester raise some defect but that is just coming due to refreshing not done since long time on your application being tested. These defects do not come on developer machines so got rejected.

  7. Some times developers do not check it carefully(there may some negligence on their part). In this case tester should consult developer and try to reproduce the defect on their machines.


You can add all the missing issues related to assert:

  • the same server side state (database state, source code, etc..)

  • the same client side state (browser version, browser extensions and configuration, resources loaded from the server - like javascript, css and html files).

Here is important to check whether all those loaded files are the same... for example if some of those files are being cached in production by some proxy server the user might be loading a javascript, css, etc... from an older release. It is good to tell the user to clear the browser cache before reproducing the error. If the error is gone then you need to adjust the headers that control the cache expiry.

  • the workflow that reproduces the error. Here you can check if the error scenario doesn't depend on concurrent iterations of another users, or some specific calculation that depend of the server or client time of the iterations.

Every software qa company follow a process of reporting defects to Dev. Below could be the reasons for non-reproducible defects:

  1. QA engineer should make sure that the latest build is installed on QA and Dev side while reproducing the issue.
  2. Browser and browser version can be different on Dev/QA side.
  3. Make sure that pre-requisite and steps to reproduce are properly defined in the defect tracking system.
  4. Browser cache can be the problem. So, it would be better if both QA/Dev can reproduce the issue after clearing the browser cache.
  5. Screen resolution may be incompatible.
  6. Adding screenshot and screencast in the defect can help to resolve this problem.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.