Unable to load dialect org.drools.compiler.rule.builder.dialect.mvel.MVELDialectConfiguration

Question

I am using Drools in my java project. Here is the pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.myproject.java</groupId>
<artifactId>PriceAnalyzer</artifactId>
<version>1</version>

<dependencies>
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>knowledge-api</artifactId>
        <version>${drools.version}</version>
    </dependency>
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-core</artifactId>
        <version>${drools.version}</version>
    </dependency>
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-compiler</artifactId>
        <version>${drools.version}</version>
    </dependency>
</dependencies>
<properties>
    <drools.version>6.2.0.Final</drools.version>
    <jbpm.version>6.2.0.Final</jbpm.version>
</properties>

This project is added into another project as a Maven dependency as below.

<dependency>
        <groupId>com.myproject.java</groupId>
        <artifactId>PriceAnalyzer</artifactId>
        <version>1</version>
        <scope>compile</scope>
</dependency>

Everything is working properly in local server. But when I deploy this in the production server it gives following exception.

java.lang.RuntimeException: Unable to load dialect 'org.drools.rule.builder.dialect.mvel.MVELDialectConfiguration:mvel:org.drools.rule.builder.dialect.mvel.MVELDialectConfiguration'
    at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.addDialect(KnowledgeBuilderConfigurationImpl.java:375)
    at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.buildDialectConfigurationMap(KnowledgeBuilderConfigurationImpl.java:361)
    at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.init(KnowledgeBuilderConfigurationImpl.java:233)
    at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.init(KnowledgeBuilderConfigurationImpl.java:193)
    at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.<init>(KnowledgeBuilderConfigurationImpl.java:183)
    at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.<init>(KnowledgeBuilderImpl.java:265)
    at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.<init>(KnowledgeBuilderImpl.java:196)
    at org.drools.compiler.builder.impl.KnowledgeBuilderFactoryServiceImpl.newKnowledgeBuilder(KnowledgeBuilderFactoryServiceImpl.java:39)
    at org.kie.internal.builder.KnowledgeBuilderFactory.newKnowledgeBuilder(KnowledgeBuilderFactory.java:46)
    at com.codegen.rm.MarkupCalculation.createKnowledgeBaseFromSpreadsheet(MarkupCalculation.java:44)
    at com.codegen.rm.MarkupCalculation.runAlgorithm(MarkupCalculation.java:23)
    at it.codegen.rnd.rm.service.ChartCalculationService.getMarkupChartData(ChartCalculationService.java:668)
    at it.codegen.rnd.rm.controller.ChartController.sendMarkupChartData(ChartController.java:260)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:817)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:731)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:968)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:870)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:844)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at it.codegen.rnd.rm.config.CORSFilter.doFilter(CORSFilter.java:31)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassCastException: org.drools.rule.builder.dialect.mvel.MVELDialectConfiguration cannot be cast to org.drools.compiler.compiler.DialectConfiguration
    at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.addDialect(KnowledgeBuilderConfigurationImpl.java:370)
    ... 48 more

Any suggestions ?

Answer 1

I had the same error. The problem was there was another version of drools-compiler in the shared tomcat libraries folder (/usr/share/tomcat7/lib). After deleting the .jar from there, the error disappeared.

I hope that helps you.