Apache httpclient 4.3.1 java.lang.NoSuchFieldError: INSTANCE

I am developing a Java EE web application.

here is my pom.xml:

<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>bitcoin</groupId> <artifactId>bitcoin</artifactId> <packaging>war</packaging> <version>1.0-SNAPSHOT</version> <name>Chens Bitcoin Webapp</name> <url>http://maven.apache.org</url> <properties> <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <!-- Define the version of the JBoss BOMs we want to import to specify tested stacks. --> <version.jboss.bom>1.0.5.CR6</version.jboss.bom> </properties> <repositories> <repository> <id>prime-repo</id> <name>Prime Repo</name> <url>http://repository.primefaces.org</url> </repository> </repositories> <dependencyManagement> <dependencies> <!-- Define the version of JBoss' Java EE 6 APIs we want to use --> <!-- JBoss distributes a complete set of Java EE 6 APIs including a Bill of Materials (BOM). A BOM specifies the versions of a "stack" (or a collection) of artifacts. We use this here so that we always get the correct versions of artifacts. Here we use the jboss-javaee-6.0-with-security stack (you can read this as the JBoss stack of the Java EE 6 APIs with Security). You can actually use this stack with any version of JBoss AS that implements Java EE 6, not just JBoss AS 7! --> <dependency> <groupId>org.jboss.bom</groupId> <artifactId>jboss-javaee-6.0-with-security</artifactId> <version>${version.jboss.bom}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> 

 <dependency> <groupId>javax</groupId> <artifactId>javaee-web-api</artifactId> <version>7.0</version> <scope>provided</scope> </dependency> <!--<dependency>--> <!--<groupId>org.jboss.spec.javax.faces</groupId>--> <!--<artifactId>jboss-jsf-api_2.2_spec</artifactId>--> <!--<version>2.2.0</version>--> <!--</dependency>--> <!--<dependency>--> <!--<groupId>com.sun.faces</groupId>--> <!--<artifactId>jsf-spi</artifactId>--> <!--<version>1.0</version>--> <!--</dependency>--> <!-- Rewrite --> <dependency> <groupId>org.ocpsoft.rewrite</groupId> <artifactId>rewrite-servlet</artifactId> <version>2.0.8.Final</version> </dependency> <dependency> <groupId>org.ocpsoft.rewrite</groupId> <artifactId>rewrite-config-prettyfaces</artifactId> <version>2.0.8.Final</version> </dependency> <dependency> <groupId>org.omnifaces</groupId> <artifactId>omnifaces</artifactId> <version>1.6</version> </dependency> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3</version> </dependency> <dependency> <groupId>org.primefaces</groupId> <artifactId>primefaces</artifactId> <version>3.5</version> </dependency> <!-- Data time management --> <dependency> <groupId>joda-time</groupId> <artifactId>joda-time</artifactId> <version>2.2</version> </dependency> <dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.9</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.3.1</version> </dependency> <dependency> <groupId>com.googlecode.json-simple</groupId> <artifactId>json-simple</artifactId> <version>1.1.1</version> </dependency> <!-- Import the PicketLink API, we deploy this as library with the application, and can compile against it --> <dependency> <groupId>org.picketlink</groupId> <artifactId>picketlink-core-api</artifactId> </dependency> <!-- Import the PicketLink implementation, we deploy this as library with the application, but can't compile against it --> <dependency> <groupId>org.picketlink</groupId> <artifactId>picketlink-core-impl</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> </dependencies> <build> <finalName>bitcoin</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.1</version> <configuration> <source>1.7</source> <target>1.7</target> <compilerArguments> <endorseddirs>${endorsed.dir}</endorseddirs> </compilerArguments> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.3</version> <configuration> <failOnMissingWebXml>false</failOnMissingWebXml> </configuration> </plugin> <plugin> <groupId>org.jboss.as.plugins</groupId> <artifactId>jboss-as-maven-plugin</artifactId> <version>7.4.Final</version> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-dependency-plugin</artifactId> <version>2.6</version> <executions> <execution> <phase>validate</phase> <goals> <goal>copy</goal> </goals> <configuration> <outputDirectory>${endorsed.dir}</outputDirectory> <silent>true</silent> <artifactItems> <artifactItem> <groupId>javax</groupId> <artifactId>javaee-endorsed-api</artifactId> <version>7.0</version> <type>jar</type> </artifactItem> </artifactItems> </configuration> </execution> </executions> </plugin> </plugins> </build> </project> 

I have a method to create HttpClient, it works fine alone, but having problem when calling from jsf page:

 public void doSth() { ...... HttpClient httpclient = HttpClientBuilder.create().build(); ...... } 

this method is invoked by commonbutton on JSF page, when button clicked following error occurred:

 Caused by: java.lang.NoSuchFieldError: INSTANCE at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:52) [httpcore-4.3.jar:4.3] at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:56) [httpcore-4.3.jar:4.3] at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<clinit>(DefaultHttpRequestWriterFactory.java:46) [httpcore-4.3.jar:4.3] ...... 

googled it, seems httpclient jar file has conflict with some other class, but I really can't figure out which one, and all dependencies in pom are necessary.

BTW, I am using WildFly 8 CR as server.

Thanks in advance.