commons-java | Handy , general purpose Java classes | Reflection library

The mchange-commons-java dependancy is unnecessary since it is contained in the com.mchangec3p0 dependancy. Replace your pom.xml with this:

I can't comment on the larger failover issue, but you certainly can define a ConnectionTester that does basically anything you want. See the apidocs for the UnifiedConnectionTester interface for concise instructions.

c3p0's built-in ConnectionTester uses Statement.executeQuery(...) so INSERTs etc may not work. Your custom ConnectionTester can do whatever it wants. You should be sure it does something sane if preferredTestQuery and rootCauseOutParamHolder are set null (in either method).

If you wish you may ignore preferredTestQuery, or require that it be null (ie throw an Exception if preferredTestQuery is set).

It appears that you are having a clash with dependency versions.

The method org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$EnableWebMvcConfiguration.addDefaultHandlerExceptionResolvers(Ljava/util/List;)V existed in Spring Boot 2.1, but is not in Boot 2.2 and later. The chain that tries to call that method starts with org.zalando.problem.spring.web.advice.security.SecurityProblemSupport.

It appears that the latest version of zalando.problem-spring-web builds against Boot 2.2.6, but you might be using an older version of zalando that builds against an older version of Boot.

Make sure that you are really getting the expected versions of Spring Boot and Spring Framework, and that the version of the zalando library is compatible with Boot 2.3.1.

Thanks to @Simon finally solved that issue and moving to next stage. I also had to modify my pom.xml's file build section using this article (https://crunchify.com/how-to-create-build-java-project-including-all-dependencies-using-maven-maven-resources-maven-dependency-maven-jar-plugin-tutorial/). Maybe somebody will find it helpful.

Thanks to @StanislavL for the tip! If you change the version of the used hibernate-search module to "5.4.0. Final", the error disappears. I have not tested newer versions yet.

Problem could be the dependency for spring-data-releasetrain on the Fowler-SR2 release train version.

This release train is a few years old see the maven pom. You'll want to take a look as to why that is included in your pom.

It looks like you are reference the mchange c3p0 framework in your code but I don't see a reference to that in your pom file.

Trying adding this as a dependency in your pom file:

The issue was caused by the mainClassName attribute in gradle.properties leading to the exception. Removing it from gradle.properties fixed the issue.

Timeout errors are typically an error not caused by your application itself - it's a problem with the connection to the SQL database.

If you are working on the DB locally, then you can check the timeout settings and modify them in order to cope with the delay in the request calls.

If you are working on a remote DB m/c, then maintaining a consistent Connection is needed. If you are unsure about how to keep the connection consistent with your machine to the DB machine, then write a simple batch script which pings the DB server and keeps the Connection alive for your application to send a request.