Upgrading To Spring Boot 2.4.0 Breaks Legacy Applications - spring-boot

Question

I'm upgrading a set of legacy applications to Spring Boot 2.4.0, running on OpenJDK 8, deployed to Pivotal Cloud Foundry.
The app and all its unit tests ran perfectly under Spring 2.3.4-RELEASE before I started this upgrade.
There was work to be done right off the bat: Spring Boot 2.4.0 brings in JUnit 5.x, so I had to fix all the JUnit 4.x tests to use the new annotations and classes.
After fixing all the tests I tried to run in IntelliJ 2020.2. All the tests failed, for the same reason: java.lang.IllegalStateException: Failed to load ApplicationContext. The root of the stack trace gives this cause:
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.context.properties.ConfigurationBeanFactoryMetadata
They removed a fundamental class from Spring Boot for the sake of Kubernetes, from the sound of it. I'm not sure I see why.
I did a Google search and found this explanation and fix.
I added spring.config.use-legacy-processing to my application.yml and a test application.properties file:
spring:
config:
use-legacy-processing: true
Still no joy - all the tests fail.
I'm confused by other links I've seen. Is this an issue with spring-cloud-dependencies? I'm reading that there might an issue with the Hoxton version. Do I need to add it to my app? It never needed this dependency before the upgrade:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Hoxton.SR9</version>
<type>pom</type>
<scope>import</scope>
</dependency>
The problem is bigger than the tests. If I ignore them and try to run the app I still fail:
ERROR [main]: Application run failed |ApplicationName=Risk_Advisor | sourcedfrom=ERROR
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'configurationPropertiesBeans' defined in class path resource [org/springframework/cloud/autoconfigure/ConfigurationPropertiesRebinderAutoConfiguration.class]: Post-processing of merged bean definition failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [org.springframework.cloud.context.properties.ConfigurationPropertiesBeans] from ClassLoader [sun.misc.Launcher$AppClassLoader#18b4aac2]
The root cause is the same:
java.lang.NoClassDefFoundError: org/springframework/boot/context/properties/ConfigurationBeanFactoryMetadata

Answer 1

when ever you do upgrades on spring, pls always look at the spring / cloud compatibility matrix and then upgrades the versions for both spring and cloud accordingly:
Also, pls note that you may not have added spring cloud as direct dependency but it may be coming into your final jar as a transitive dependency so its always better to add below spring cloud dependency as direct dependency management in your pom to stay away from any conflicts:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring.cloud-version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>

Answer 2

I got the same error when migrating to Spring Boot 2.4.4 which forced me to migrate to Spring Cloud 2020.0.1 as well. In my case, the error was due to Bootstrap, provided by spring-cloud-commons, not being any longer enabled by default. I had to re-enabled it by adding the following new starter in my build.gradle file as stated here:
implementation 'org.springframework.cloud:spring-cloud-starter-bootstrap'
You say your app doesn't use Spring Cloud, so I'm not sure why you ended up facing which seems to be the same issue. Hopefully this workaround might work for you and help out others using Spring Cloud.
To fix the failing JUnit 4 tests, I have just added it as a dependency:
testImplementation 'junit:junit:4.13'

Answer 3

I had the same error for JUnit 4 tests after migration my project to Spring Boot 2.5.6. Adding JUnit 4 dependencies did not fix this error as well as migration JUnit 4 tests to JUnit 5. My project does not define Spring Cloud dependencies in build.gradle so in order to find where those dependencies come from I simply ran gradle command:
gradle dependencyInsight --dependency org.springframework.cloud
and saw that spring cloud dependencies were pulled within one of the custom libraries. Upgrade spring cloud dependencies to a compatible version there and reimport custom library fixed the error.