Context and Motivation] Requirements engineering (RE) is central to software development. Despite its importance, there are many issues related to its enactment. Question and answer platforms, such as the Stack Exchange, are paramount in contemporary software development. They discuss and bring to light practitioners’ viewpoints on software engineering issues. Approaching those platforms focusing on RE deserves investigation because it can reveal current issues experienced by software practitioners and possible solutions for them. [Question/Problem] This work investigates RE issues, their causes, effects, and possible solutions as discussed by software practitioners in the Software Engineering Stack Exchange (SWESE). For that, we mine, curate, and analyze a set of 61 discussions related to RE, composed of 414 posts and 770 comments extracted from SWESE. [Principal Ideas/Results] We identify 50 issues and their relations with requirements phases. Customers’ unable to describe system requirements and the need for detailed specifications are among the most commonly discussed issues. We also list 20 causes, 23 effects, and 59 solutions for the mined issues. Examples of causes for RE issues are lack of technical knowledge and communication issues. Examples of the effects of RE issues are rework and unstable requirements. Solutions encompass practices such as clearly defining requirements and using prototypes. [Contribution] This work organizes the mined RE issues in a Sankey diagram, relating them to RE phases and solutions, which may assist practitioners experiencing them and serve as guidance for future research.