Скачать или смотреть Fixing the Failed to instantiate [javax.servlet.Filter] Error in Spring Boot 2.6.2

Learn how to resolve the `Failed to instantiate [javax.servlet.Filter]` issue that arises in Spring Boot 2.6.2 due to security configuration problems.
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This video is based on the question https://stackoverflow.com/q/72270270/ asked by the user 'cc gogo' ( https://stackoverflow.com/u/11955274/ ) and on the answer https://stackoverflow.com/a/72270621/ provided by the user 'Andrey Grigoriev' ( https://stackoverflow.com/u/14998237/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Failed to Instantiate Filter Error in Spring Boot 2.6.2

If you've recently upgraded your Spring Boot version to 2.6.2, you might be encountering an error that can halt your application's functionality. Specifically, the error message is:

[[See Video to Reveal this Text or Code Snippet]]

This issue pertains to the configuration of Spring Security in your application, particularly in the way the security policies are set up in your WebSecurityConfigurerAdapter subclass. Below, we will delve into the reasons behind this error and how you can effectively resolve it.

The Problem: Error Breakdown

The error arises when the Spring Security configuration attempts to set up URL pattern security rules incorrectly. Here's an important point to understand:

After you call super.configure(http), Spring Security sets up the default security configuration which concludes with this line:

[[See Video to Reveal this Text or Code Snippet]]

This line effectively locks down all requests after all prior configurations, meaning you can no longer specify rules like antMatchers after this point.

Solution: Modify Your Security Configuration

To resolve this issue, you need to modify your security configuration. Here’s how you can do it step-by-step:

1. Avoid Calling super.configure(http)

Instead of relying on the default security setup provided by Spring, you can directly implement your custom configurations. This will prevent the error from occurring while allowing you to define your security rules as needed. Here’s an updated snippet of your code:

[[See Video to Reveal this Text or Code Snippet]]

2. Rethink Your Security Sequence

By removing the call to super.configure(http), you retain complete control over how requests should be authenticated and flexibly structure your policies without any restrictions that come from the default behavior.

3. Test Your Configuration

Once you've made these changes, it’s crucial to test your application thoroughly. Verify that the security settings behave as expected, and ensure that routes requiring authentication are operating correctly.

Conclusion

Upgrading libraries often comes with challenges, but understanding the underlying changes in behavior can lead to effective solutions. If you encounter the Failed to instantiate [javax.servlet.Filter] error after upgrading to Spring Boot 2.6.2, simply adjusting your security configuration according to the steps outlined above should resolve the issue.

With these changes, you can enjoy the benefits of using the latest Spring Boot features without the hassle of security configuration bugs. Keep your application secure and efficient!