E38388e383a9e38396e383abe382b7e383a5e383bce38386e382a3e383b3e382b0 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