SpringBoot 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

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

<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>

Comment From: ThomasVitale

The opentelemetry-spring-boot-starter is provided by the OpenTelemetry Java Instrumentation project and it's probably not supporting Spring Boot 4 yet. I would suggest raising an issue on that project's GitHub for supporting the upcoming Spring Boot 4: https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues

Comment From: bclozel

Yes the Spring Boot team does not support this starter.