This document analyzes build failures in the continuous integration workflows of Java-based open source software projects. It categorizes common error types that cause build failures, such as compilation errors, test failures, dependency errors and crashes. It also uses statistical analysis to study factors that may be associated with build failures, such as change metrics, previous build results, and pull request scenarios. A key finding is that build failures often occur consecutively, indicating phases of instability that perpetuate failures. The analysis provides insights into challenges of mining continuous integration data and understanding the causes of build failures.