What is Intermittent issue in Testing? How do we find it?


The simple answer is: an issue that occurs at an irregular interval or not in a continuous or steady manner.

Another way to define this "a mysterious and undesirable behavior of a system, observed at least once, that we cannot yet manifest on demand." - James Bach.

What are some examples of this?

In my experience, race condition issues come to mind as these can look intermittent when they are found.

A race condition, by definition, is dependent on a sequence of events or timing of events. If an event/process happens out of order or a secondary process finishes first where the results are dependent on the first process finishing, a bug occurs. This looks intermittent due to the user/tester not being aware of the order of events that need to occur.

Another way this occurs is due to a caching issue. When one person has an issue that can't be replicated by another, we often tell that person to "clear their cache/cookies" and the problem goes away. This is one of the simplest explanations and we usually don't expound upon it afterwards.

Because software is complex, there are lots of reasons why intermittent issues occur: hardware going bad, lack of CPU or memory resources, a 3rd party dependency is going awry, etc.

Just because an issue happens once doesn't mean it was a fluke and is unlikely to occur again. Be cautious of when these occur as it's likely to occur again.


An intermittent issue is a problem caused by components of your system that you are not paying attention / not under control when testing.


An inconsistent bug which cannot be reproduced reliably every time with same set of steps.


Intermittent Bugs are the kind of bugs which are not having predictable conduct. Means assuming you execute same test twice on any application, each time it will give you some unique outcome. Might be you get it again on executing third time.

  • Welcome to the community. While you have defined what intermittent means, the second part of the question is "how do you find it". How would you update your answer with how to find intermittent bugs?
    – Lee Jensen
    Dec 1 '21 at 18:29

The easiest definition of the intermittent issues in testing could be unexpected random errors that testers have to deal with. Most of the time, these issues are triggered because of unanticipated reasons.

Also, the intermittent issues can also be understood as inconsistent behavior of the application for multiple test efforts made on a build while sticking to the same process. All in all, it is more an error or bug that occurs in a short time and not repeatedly

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