The bean validation api is on the classpath but no implementation could be found

This error message usually means that your application is trying to use the Bean Validation API, which is a set of annotations and interfaces for validating Java Beans, but there is no implementation of this API available on your classpath.

To solve this issue, you need to add an implementation of the Bean Validation API to your project's dependencies. The most common implementation is Hibernate Validator. You can add it to your project by adding the following dependency to your build file:

<dependency>
  <groupId>org.hibernate.validator</groupId>
  <artifactId>hibernate-validator</artifactId>
  <version>6.2.0.Final</version>
</dependency>

After adding this dependency, make sure to rebuild your project and redeploy it to your server. This should resolve the error message and allow you to use the Bean Validation API in your application.