Key New Features in Spring Boot 2.6.0 Release

Spring Boot 2.6.0 has been officially released, bringing several important upgrades for backend developers.

1. Circular Dependency Prohibition

Circular dependencies, a common interview topic, are now prohibited by default; if a cycle exists the application fails to start with an error message suggesting the use of spring.main.allow-circular-references=true as a last resort.

┌─────┐
|  a (field private com.zhiyin.TestB com.zhiyin.TestA.b)
↑      ↓
|  b (field private com.zhiyin.TestA com.zhiyin.TestB.a)
└─────┘

Action:
Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans. As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.

As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.

To allow the cycle, add the following property to application.properties: spring.main.allow-circular-references = true The application can then start normally.

2. Custom Sanitizing Rules

Spring Boot 2.6.0 supports custom sanitizing for the /env endpoint and configprops by defining a bean of type SanitizingFunction.

@Bean
public SanitizingFunction pwdSanitizingFunction() {
    return data -> {
        org.springframework.core.env.PropertySource<?> propertySource = data.getPropertySource();
        String key = data.getKey();

        // Only sanitize certain keys in redis.properties
        if (propertySource.getName().contains("redis.properties")) {
            if (key.equals("redis.pwd")) {
                return data.withValue(SANITIZED_VALUE);
            }
        }
        return data;
    };
}

This provides flexible data masking.

3. Redis Connection Pool Enabled by Default

Previously, enabling a Redis connection pool required manual configuration; from 2.6.0 it is on by default. To disable it, set one of the following properties: spring.redis.jedis.pool.enabled = false or

spring.redis.lettuce.pool.enabled = false

4. WebTestClient Support for MVC Testing

Developers can use WebTestClient in mock environments by adding the @AutoConfigureMockMvc annotation, simplifying test code.

5. New Path Matching Strategy

The default path‑matching strategy switched from AntPathMatcher to PathPatternParser. It can be reverted by setting spring.mvc.pathmatch.matching-strategy=ant-path-matcher. The new parser retains compatibility except for the unsupported “**” pattern, and adds support for {*pathVariable}.

public static class Pathmatch {
    private MatchingStrategy matchingStrategy =
            MatchingStrategy.ANT_PATH_MATCHER;
}

public static class Pathmatch {
    private MatchingStrategy matchingStrategy =
            MatchingStrategy.PATH_PATTERN_PARSER;
}

6. Enhanced /info Endpoint

The /info endpoint now includes detailed Java runtime information, for example:

{
  "java": {
    "vendor": "BellSoft",
    "version": "17",
    "runtime": {
      "name": "OpenJDK Runtime Environment",
      "version": "17+35-LTS"
    },
    "jvm": {
      "name": "OpenJDK 64-Bit Server VM",
      "vendor": "BellSoft",
      "version": "17+35-LTS"
    }
  }
}

7. Other Changes

Servlet applications now support the SameSite attribute on cookies.

Health groups can be configured on the main or management port.

Classes, methods, and properties deprecated in Spring Boot 2.4 have been removed.

Log4j2 composite configuration is now supported.

Build‑info property exclusions are supported.

Note that Spring Boot releases two minor versions each year with one‑year free support; version 2.4.x is no longer supported.