Main Types of Defects in Software Testing

October 1110:002011 by Nataliia VasylynaPrint This Article

Note: the article was updated in August 2018.

There are several different classifications of software issues that are based on a certain criterion, for example, classification according to defect severity, probability, and priority.

Software defects according to their severity

When it comes to bug severity, there four major types:

Critical – issues that require immediate removal, affect core functionality of the product and can cause system crashes or block software operability
Major – defects that affect main system functions but do not cause crash-down of the whole system
Minor – bugs that do not have much impact on system functionality and do not affect workflow but that can have a negative impact on user experience
Trivial – issues that are not related to system functionality and that can be skipped, e.g., spelling mistakes.

Defect probability is a parameter that defines the possibility of the issue to occur and to be detected by the end users. According to this criteria, there are high, medium and low probability defects.

In terms of business purposes, defects can be classified as high, medium and low priority issues. Defects with high priority should be fixed at first as they affect the business needs.

Also, there is such a classification of defects in software testing:

Extra defects

A requirement incorporated into the product that wasn’t given by the client. This is usually a discrepancy from the project specification, but it also may be a characteristic requested by the end users. Nevertheless, it is considered as a defect as it does not meet the existing requirements.

Missing defects

The requirement given by the client was not done. This also is a discrepancy from the specifications – a feature that should not be implemented according to the spec. It also may mean that the client’s requirement wasn’t noted appropriately.