Caused by: java.lang.NoClassDefFoundError: org/springframework/http/MediaType

This error occurs when the required class "org.springframework.http.MediaType" is not found in the classpath during runtime.

Possible causes and solutions for this error are:

1. Missing dependency: Check if the required Spring framework dependency is added to your project's classpath. You can add the dependency in your project's pom.xml file if you are using Maven.

2. Version mismatch: Ensure that the version of the Spring framework that you are using is compatible with the version of the MediaType class you are trying to use.

3. Classpath issue: Check if the classpath is set up correctly. Make sure that the required jar files are included in the classpath and that they are accessible during runtime.

4. Incorrect package name: Check if the package name of the MediaType class is correct. If necessary, update the import statement to import the correct package.

5. Compilation issue: Check if the code is compiled without any errors. If there are any compilation errors, fix them first before trying to run the code.