E8b5b7e58b95e382a8e383a9e383bc Articles

Spring Boot App Won't Start: Root Cause Analysis and Solutions

A comprehensive guide for troubleshooting the 'APPLICATION FAILED TO START' error. Covers how to read FailureAnalyzer output, using the --debug flag, and solutions for major patterns including port conflicts, duplicate Bean definitions, circular references, missing DataSource configuration, and profile misconfigurations with practical examples.

2026-05-29