Most software quality research has focused on identifying faults (i.e. information is incorrectly recorded in an artifact). Because software still exhibits incorrect behavior, a different approach is needed. This paper presents a systematic literature review to understand whether using information about the source of a fault (i.e. and error) can be helpful. Once the usefulness of errors is established, then it is important to identify and classify errors. The review identified 149 papers from software engineering, psychology and human cognition that provided information about the sources of requirements faults. A major result of this paper is a categorization of the sources of faults into a formal taxonomy that provides a starting point for future research into error-based approaches to improving software quality.