Java Stack Trace Analyzer

Find the root cause of a Java stack trace, what it means and how to fix it.

How to use the Java Stack Trace Analyzer

1. Paste a stack trace or a whole log (Spring Boot, Logback, Log4j, Gradle, Maven), or click Sample.
2. Optionally enter your base package so the tool finds your own code in the trace.
3. Read the most likely cause and the fixes; every exception in the "Caused by" chain is checked.

What it recognizes

• JDK: NullPointerException (including the variable in Java 14+ messages), ClassCastException, index errors, ConcurrentModificationException, immutable collections, number and date parsing, enum values.
• Class loading and memory: dependency version conflicts, missing classes (including javax → jakarta), class file versions, every kind of OutOfMemoryError, and infinite recursion.
• Spring: missing, duplicate and circular beans, port in use, missing DataSource, validation, unreadable bodies, Content-Type and method errors, Spring Security access denied.
• Data: Jackson, Hibernate lazy loading, optimistic locking, detached entities, constraint violations, Hikari pool exhaustion, unreachable databases, login failures, missing tables and deadlocks.
• Network: connection refused, timeouts, DNS failures, untrusted and mismatched TLS certificates.

Frequently asked questions

Why start from the root cause?

The top exception is usually a wrapper (like BeanCreationException or JpaSystemException) added on the way up. The last "Caused by" is where things actually went wrong.

Is my stack trace uploaded?

No. It's analyzed in your browser with rules, not sent to a server or an AI service.