Why Do GitHub Actions Workflows Fail? An Empirical Study

GitHub Actions (GHA), a built-in continuous integration and continuous delivery (CI/CD) service of GitHub, has been widely adopted by developers, streamlining the automation of software development workflows. Despite its popularity, failures frequently occur during GHA workflow executions. Fixing these failures often requires significant human effort, and unsuccessful workflow executions waste computing resources. Understanding the reasons behind workflow failures could provide valuable insights for troubleshooting the existing issues of CI/CD and further improving the development process. In this paper, we present an empirical study to reveal the reasons behind GHA workflow failures. By manually analyzing 375 failed workflow executions across 260 open-source Java projects, we built a comprehensive taxonomy categorizing the common failure types. The taxonomy was further validated by surveying 151 developers. This study is the first empirical work to analyze GHA workflow failures, bringing valuable knowledge to the field of continuous integration in software engineering. Moreover, our taxonomy and survey results not only underscore the critical need for better tools and practices to mitigate these failures but also indicate the directions to enhance the efficiency and reliability of CI/CD pipelines.