Spring 4.0.0-M1 causes ClassNotFoundException on org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration when using opentelemetry-instrumentation-bom and opentelemetry-spring-boot-starter

[Algieba4]

Describe the bug

I tested Spring 3.5 -> 4.0.0-M1 version upgardes on two programs. One of them went well and the other didn't. Investigating further on the difference between the two, I noticed one was using the opentelemetry-spring-boot-starter dependancy and the other was not. Commenting out opentelemetry-instrumentation-bom (version 2.18.1) and opentelemetry-spring-boot-starter allowed my second program to run.

Interestingly, I didn't have any issues with maven clean, test, or install. All my test cases ran successfully, it was only when I tried running my program that it failed with the following error:

2025-08-01T14:26:43.327-05:00 ERROR 15881 --- [           main] [                                                 ] o.s.boot.SpringApplication               : Application run failed

java.lang.IllegalArgumentException: Could not find class [org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:353) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.TypeMappedAnnotation.adapt(TypeMappedAnnotation.java:451) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.TypeMappedAnnotation.getValue(TypeMappedAnnotation.java:384) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.TypeMappedAnnotation.asMap(TypeMappedAnnotation.java:273) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.AbstractMergedAnnotation.asAnnotationAttributes(AbstractMergedAnnotation.java:191) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.AnnotationBeanNameGenerator.determineBeanNameFromAnnotation(AnnotationBeanNameGenerator.java:143) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.AnnotationBeanNameGenerator.generateBeanName(AnnotationBeanNameGenerator.java:110) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.registerBeanDefinitionForImportedConfigurationClass(ConfigurationClassBeanDefinitionReader.java:164) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:144) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:123) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:454) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:306) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:349) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:118) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:782) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:600) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.boot.web.server.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-web-server-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:435) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1344) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1333) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at com.example.mcssps.McsSps.main(McsSps.java:10) ~[classes/:na]
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490) ~[na:na]
	at java.base/java.lang.Class.forName0(Native Method) ~[na:na]
	at java.base/java.lang.Class.forName(Class.java:543) ~[na:na]
	at org.springframework.util.ClassUtils.forName(ClassUtils.java:302) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:343) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	... 22 common frames omitted

Steps to reproduce

Add the following to pom.xml

...
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>4.0.0-M1</version>
    <relativePath/>
  </parent>
...
<dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>io.opentelemetry.instrumentation</groupId>
        <artifactId>opentelemetry-instrumentation-bom</artifactId>
        <version>2.18.1</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
  </dependencyManagement>
...
  <dependencies>
    <!-- OpenTelemetry Spring Boot Starter -->
    <dependency>
      <groupId>io.opentelemetry.instrumentation</groupId>
      <artifactId>opentelemetry-spring-boot-starter</artifactId>
    </dependency>
  </dependencies>

Expected behavior

Expectation is for RestClientAutoConfiguration to be automatically detected and started up using Spring 4.x

Actual behavior

2025-08-01T14:26:43.327-05:00 ERROR 15881 --- [           main] [                                                 ] o.s.boot.SpringApplication               : Application run failed

java.lang.IllegalArgumentException: Could not find class [org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:353) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.TypeMappedAnnotation.adapt(TypeMappedAnnotation.java:451) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.TypeMappedAnnotation.getValue(TypeMappedAnnotation.java:384) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.TypeMappedAnnotation.asMap(TypeMappedAnnotation.java:273) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.core.annotation.AbstractMergedAnnotation.asAnnotationAttributes(AbstractMergedAnnotation.java:191) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.AnnotationBeanNameGenerator.determineBeanNameFromAnnotation(AnnotationBeanNameGenerator.java:143) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.AnnotationBeanNameGenerator.generateBeanName(AnnotationBeanNameGenerator.java:110) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.registerBeanDefinitionForImportedConfigurationClass(ConfigurationClassBeanDefinitionReader.java:164) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:144) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:123) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:454) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:306) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:349) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:118) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:782) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:600) ~[spring-context-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.boot.web.server.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-web-server-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:435) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1344) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1333) ~[spring-boot-4.0.0-M1.jar:4.0.0-M1]
	at com.example.mcssps.McsSps.main(McsSps.java:10) ~[classes/:na]
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490) ~[na:na]
	at java.base/java.lang.Class.forName0(Native Method) ~[na:na]
	at java.base/java.lang.Class.forName(Class.java:543) ~[na:na]
	at org.springframework.util.ClassUtils.forName(ClassUtils.java:302) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:343) ~[spring-core-7.0.0-M7.jar:7.0.0-M7]
	... 22 common frames omitted

Javaagent or library instrumentation version

2.18.1

Environment

JDK: Amazon Corretto 24, maven 3.9, Spring Boot 4.0.0-M1
OS: Locally on a MacBook Pro (Apple M1 Pro), deployed to a k8s cluster

Additional context

No response

Tip

_{React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it. Learn more here.}

[laurit]

Looks like RestClientAutoConfiguration was moved to different package.

[adinauer]

Hey, we're currently starting to add support for Spring 7 / Spring Boot 4 to Sentry and have also hit this problem. We'd also love to see support. Please let us know if we can help in some way.

[UkonnRa]

+1 for this issue, just curious how the lib maintainer handle this kind of problem?

[zeitlinger]

Help on Spring 4 would be highly appreciated 😄

I can help get started - also on CNCF slack.

This is the basic structure

• https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/instrumentation/spring/spring-boot-autoconfigure/src/main/javaSpring3 is a directory for spring version specific things - this can be done for Spring boot 4 as well
• smoke tests are in https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/smoke-tests-otel-starter - we also need one for spring boot 4

[adinauer]

I'll start to take a look this week but can't say how far I'll get since this is a short week for me. I'll likely return to this in a couple weeks. Will most likely need help but I'll just give it a shot first.

[adinauer]

Hey, I've tried to duplicate springBoot3 as suggested, but wasn't able to make it work for both Spring Boot 3 and 4 at the same time due to org.springframework.boot.autoconfigure.AutoConfiguration.imports having to be different for each. I've opened #14415 to document what I tried, in case you wanna take a look or in case I've come to a false conclusion on it. I do recommend closing #14415.

I then tried duplicating spring-boot-autoconfigure and spring-boot-starter for Spring Boot 4 in #14416 which looks promising so far. After installing it in my local Maven repository, I was able to confirm this does get rid of ClassNotFoundException: org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration and allows the application to start up.

[laurit]

@adinauer We don't really want to copy everything for boot4. If it turns out to be necessary to create a separate spring-boot-autoconfigure-4.0 module, which I find unlikely, then we'd prefer to move classes that are the same in the old and new module into a separate shared module instead of duplicating them. Anyway I suspect that we can probably have separate autoconfiguration classes for boot 4 and older versions by using @ConditionalOnClass annotation so that the autoconfiguration class would only run only on the version that has the classes it uses.