Spring 'BeanCurrentlyInCreationException: Error creating bean with name ... Requested bean is currently in creation: Is there an unresolvable circular reference?' / 'The dependencies of some of the beans in the application context form a cycle': how do I fix it?

Cause: Two or more beans depend on each other, so none can be created first. With constructor injection the Spring container detects this at runtime and throws BeanCurrentlyInCreationException. Spring Boot 2.6 and later prohibit circular references by default (earlier versions tried to break the cycle automatically), so an application that upgraded from 2.5 may start failing without code changes. Fix (best first): 1. Redesign to remove the cycle. A cycle is usually a sign that two classes share a responsibility: move the shared logic into a third bean that both depend on, or replace one direction with an event or callback. 2. If one dependency is optional, make that side use setter (or field-free configuration method) injection instead of the constructor. Spring's documentation calls this a workaround and says constructor injection is preferred for mandatory dependencies. 3. As a targeted escape hatch, add @Lazy on the injection point or constructor parameter so a lazy-resolution proxy is injected and the dependency is resolved on first use. 4. Last resort in Spring Boot: set spring.main.allow-circular-references=true to restore the old behavior. It hides the design problem and lets beans be injected before they are fully initialized, so treat it as temporary. Verify: The application context starts without the exception, and with the allow-circular-references property removed if you had added it temporarily. Sources: https://docs.spring.io/spring-framework/reference/core/beans/dependencies/factory-collaborators.html https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.6-Release-Notes