The AJP Connector is configured with secretRequired="true" but the secret attribute is either null or "" after upgrade to 2.2.5

Caused by: java.lang.IllegalArgumentException: The AJP Connector is configured with secretRequired="true" but the secret attribute is either null or "". This combination is not valid.
at org.apache.coyote.ajp.AbstractAjpProtocol.start(AbstractAjpProtocol.java:264)
at org.apache.catalina.connector.Connector.startInternal(Connector.java:1035) ... 22 common frames omitted

I am seeing the above errors after upgrading Spring Boot from 2.1.9 to 2.2.5. The upgrade was necessary to overcome a Ghostcat vulnerability by upgrading Tomcat version to 9.0.31, which is being bundled with the latest Spring Boot 2.2.5.

Solution

Here is one solution, though probably not the best one, but my focus was not this, just to pass through the error, I was enabling AJP on Spring Boot 2.2.5.RELEASE version. Add this:

((AbstractAjpProtocol) ajpConnector.getProtocolHandler()).setSecretRequired(false);

My full class for AJP configuration:

package com.ssldemo.config;

import org.apache.catalina.connector.Connector;
import org.apache.coyote.ajp.AbstractAjpProtocol;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class TomcatConfiguration {

    @Value("${tomcat.ajp.port}")
    int ajpPort;

    @Value("${tomcat.ajp.remoteauthentication}")
    String remoteAuthentication;

    @Value("${tomcat.ajp.enabled}")
    boolean tomcatAjpEnabled;

    @Bean
    public TomcatServletWebServerFactory servletContainer() {

        TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory();
        if (tomcatAjpEnabled) {
            Connector ajpConnector = new Connector("AJP/1.3");
            ajpConnector.setPort(ajpPort);
            ajpConnector.setSecure(false);
            ajpConnector.setAllowTrace(false);
            ajpConnector.setScheme("http");
            ((AbstractAjpProtocol) ajpConnector.getProtocolHandler()).setSecretRequired(false);
            tomcat.addAdditionalTomcatConnectors(ajpConnector);
        }

        return tomcat;
    }

}

application.properties

server.port=8082
tomcat.ajp.port=9090
tomcat.ajp.remoteauthentication=false
tomcat.ajp.enabled=true