Which kind of requirement includes expected errors and error handling?

Functional requirements are integral to defining what a system must do, which includes detailing the expected interactions and behaviors of the application. Among these are requirements that specify how the system should handle errors, as they are directly tied to the functionality of the application. This includes specifying particular error conditions, the types of errors that can arise, and how the system should respond when such errors occur.

For instance, functional requirements may outline the need for input validation, user feedback for incorrect inputs, or recovery actions when an error is encountered. By defining these expectations, developers can ensure that the application behaves correctly under various scenarios, thereby enhancing reliability and usability.

Other types of requirements, such as non-functional or system integration requirements, do not typically focus directly on specific functional behaviors like error handling. Non-functional requirements deal with criteria that judge the operation of a system, such as performance, security, and usability but do not specify behavior in error situations. System integration requirements focus more on how different components interact rather than the specific handling of errors. User experience requirements may touch on how errors are communicated to users but do not detail the expected behaviors or solutions for those errors, which are firmly in the realm of functional requirements.