Reasons why Tester miss Software Bug

First of all, it is not a good thing on part of tester if he/she miss the Software bug, as we know how much important Testing is in Software development life cycle, but there are times when testers miss the bug. Though it is not done purposely as no tester want to leave the Software bug undetected and unreported.
There can be many reasons which can lead to miss of Software bug by a tester. Some of them are as below:

Improper Requirements

The requirement documentation is not up to the mark or adequate. As a result of which test cases prepared may not be proper, resulting in missing of many scenarios. It is quite important that test cases prepared should be clear and complete, with total coverage of requirement documentation. There are chances that requirement is not fully clear to QA persons or developer, leading to wrong testing and miss of Software bug.

Not Sufficient Testing Time

Poor strategy or insufficient time planned for testing sometimes lead to low time availability for the testers to test the application before release. Whatever is the reason for low time availability for the tester, it can lead to inadequate testing of the application, which can ultimately lead to missing of a bug by the tester.

Repetitive Testing misses Software Bug

It usually happens that testers have to do testing for same test case again and again. In such cases, due to repetitive testing, tester become irritated and tired and also sometimes leave the test case untested, assuming that it was running fine earlier. Though we are talking from a Psychological perspective, but it is fact that running the same test case, again and again, reduces the efficiency of a tester and makes them less productive.

Incomplete Regression Testing

During Regression testing, it is very difficult to find related Software bugs, sometimes an application is so large that tester is unaware of the other area of the application which is affected by fixing a bug in one place. Also, if there are many bugs in a module, then it happens that some of the bugs are detected by Tester but some related bugs are missed.

Domain Knowledge of Application

It is quite important for the tester to have domain knowledge of the subject for comprehensive testing. Lack of domain knowledge plays an important role in missing of a Software bug. Whatever is the reason for a lack of domain knowledge, whether it is a lack of time or lack of motivation of tester, it increases the chance of inadequate testing. Also, it can lead the tester to be influenced by the developer, who has developed the application, who can misinterpret the requirement to tester so as to prevent the issue from being reported to the developer for fixing.

Low Project Budget for Testing

Small testing budget and small team size hamper the quality of the application. With the development of the project, more testers required. Due to the cost factor, the limited testing resource has to do more testing, ultimately leading to compromise in the quality of the application. Though most of the issues are fixed but there are chances of few bugs being missed out. This factor especially makes an impact when there is less time for testing before release.
Frequent requirement Changes
Last minute requirement changes put too much pressure on developer and tester, this not only limits the time but also the probability of missing out defect by Software tester and also developer is more prone to create mistakes in such tight deadlines. Many times it happens that changes in the code or UI is done 2-3 days before release and gets released to production without getting noticed

Incapability of Automation Scripts

Sometimes more reliability on automation testing also lead to missing of defect as manual tester start depending more on Automation testing which lacks human experience and intuition. For Automation to succeed required good management and experienced testers.
Incapable Management
Organizational factor sometimes plays an important role. Lack of motivation in a testing team also plays an important role. Sometimes tester does not get enough recognition and are ignored in the organization because they feel Anyone can do Software Testing. Sometimes testers get less salary as compared to developers. There may be another organizational factor as well which hampers the productivity of testing resource. The bad relationship between testing team members and Test Manager or bad relationship between Testing team and development team make the situation worse.

No Proper Test Plan

Lack of Proper testing process also hampers the productivity. For example, proper Software bug tracking tool should be there, so as to track the status of the Software bug. It sometimes happens that old Software bug is lost after new Software bug is found. Proper configuration and release management process should be there.

Human Nature

Last but not the least, a human can also create mistakes. Sometimes tester is not able to reproduce issue which gets found during ad-hoc testing. The tester cannot be in alert condition all the time.
Overall, we can say that though it is not a good thing if the issue is missed by a tester and is detected by the client or end user. It not only diminishes the image of the testing team but impacts to the quality of the application because it is the QA/Tester who is responsible for ensuring the delivery of quality product to the client. On the other hand, it is also not fair to blame tester for the error occurring once in blue moon.