Troubleshooting 'Failed to introspect Class []' Error in Spring Boot

Published on 2024.02.17


When developing a Spring Boot application with Spring Security, you may encounter the error message 'Failed to introspect Class []'. This error typically occurs when there are configuration issues related to Spring Security. In this article, we will discuss the causes of this error and provide troubleshooting steps to resolve it.

Understanding the Error

The error message 'Failed to introspect Class []' usually indicates that Spring Security is unable to properly analyze the configuration settings defined in the WebSecurityConfiguration class. This class is responsible for configuring web-based security for your Spring Boot application.

Possible Causes

  1. Missing or incorrect Spring Security dependencies: Ensure that the necessary Spring Security dependencies are included in your project's pom.xml file. Verify the versions and compatibility of the dependencies as well.
  2. Misconfiguration in the WebSecurityConfiguration class: Review the configuration settings in WebSecurityConfiguration to check for any mistakes or missing required annotations.
  3. Conflict with other security-related dependencies: If you have other security-related dependencies in your project, there might be a conflict or incompatible configurations. Check for any conflicting dependencies and resolve them.

Troubleshooting Steps

  1. Verify Spring Security Dependencies: Double-check the pom.xml file and ensure that all necessary Spring Security dependencies are present with the correct versions. Consider updating them if needed.
  1. Review WebSecurityConfiguration: Inspect the WebSecurityConfiguration class for any misconfigurations. Ensure that the class is correctly annotated with @Configuration and @EnableWebSecurity.
public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {
  1. Check for Conflicting Dependencies: Look for any other security-related dependencies in your project's pom.xml file. If there are any conflicts, try to resolve them by explicitly excluding or updating the dependencies.
  1. Clean and Rebuild: Clean and rebuild your project to ensure all dependencies are correctly resolved and configured.


The 'Failed to introspect Class []' error can be frustrating, but by following the troubleshooting steps outlined in this article, you should be able to identify and resolve the underlying issues. Remember to carefully review your Spring Security configuration and ensure that all necessary dependencies are included and correctly configured.


Spring, Spring Boot, Spring Security, Troubleshooting, Error Handling