I managed to upgrade my Errai 2.4.3 app to be deployable on Wildfly 8 Final. The Wildfly 8 CDI is pretty picky and until the Weld developers fix in late March (and propagate the fix to Wildfly 8 release, who knows when) here is what to do:

1. You need use to upgrade Guava 14.0.1 to Guava 16.0.1

2. You need to lose errai cordova

You will still get some Errai warnings, but your app would deploy:

===========================

23:14:20,134 WARN  [org.jboss.weld.Event] (MSC service thread 1-3) WELD-000411: Observer method [BackedAnnotatedMethod] public org.jboss.errai.cdi.server.CDIExtensionPoints.observeResources(@Observes ProcessAnnotatedType<Object>) receives events for all annotated types. Consider restricting events using @WithAnnotations or a generic type with bounds.

23:14:20,200 INFO  [org.jboss.errai.cdi.server.CDIExtensionPoints] (MSC service thread 1-3) starting errai cdi ...

23:14:21,098 INFO  [org.jboss.errai.common.metadata.MetaDataScanner] (Thread-69) added class scanning extensions: org.jboss.errai.common.metadata.JbossVFsTypeHandler

23:14:21,596 INFO  [org.jboss.errai.reflections.Reflections] (Thread-69) Reflections took 496 ms to scan 14 urls, producing 438 keys and 2256 values [using 2 cores]

23:14:21,658 INFO  [org.jboss.errai.cdi.server.CDIExtensionPoints] (pool-6-thread-1) all services registered successfully

23:14:21,788 WARN  [org.jboss.weld.Validator] (weld-worker-1) WELD-001473: javax.enterprise.inject.spi.Bean implementation org.jboss.errai.cdi.server.ErraiServiceBean@745553e declared a normal scope but does not implement javax.enterprise.inject.spi.PassivationCapable. It won't be possible to inject this bean into a bean with passivating scope (@SessionScoped, @ConversationScoped). This can be fixed by assigning the Bean implementation a unique id by implementing the PassivationCapable interface.

23:14:21,789 WARN  [org.jboss.weld.Validator] (weld-worker-1) WELD-001473: javax.enterprise.inject.spi.Bean implementation org.jboss.errai.cdi.server.MessageBusBean@557c80d8 declared a normal scope but does not implement javax.enterprise.inject.spi.PassivationCapable. It won't be possible to inject this bean into a bean with passivating scope (@SessionScoped, @ConversationScoped). This can be fixed by assigning the Bean implementation a unique id by implementing the PassivationCapable interface.

===========================

Here is what my Gradle file looks like:

===================================

//This project uses ideas for GWT from:

//  https://github.com/kompot/gwtupld/blob/master/build.gradle

//  https://github.com/kompot/waveed/blob/master/build.gradle

//  http://www.prait.ch/wordpress/?p=347

//  https://code.google.com/p/pigwt/source/browse/trunk/build.gradle?r=22

//  https://github.com/davidecavestro/smartgwt-test-case/blob/master/build.gradle

project.description = "stocks 4 grab gwt web application"

//Project properties

project.ext {

    erraiVersion = "2.4.3.Final"

    warDir = "${project.buildDir}/war"

    webInfDir = "${project.warDir}/WEB-INF"

    webLibDir = "${project.webInfDir}/lib"

    webClassesDir = "${project.webInfDir}/classes"

    webResourcesDir = "${project.webInfDir}/resources"

    gwtExtraDir = "${project.buildDir}/extra"

    deployedWarDir = "${wildfly_root}/standalone/deployments/${project.name}.war"

}

apply plugin: "war"

apply plugin: "eclipse-wtp"

//Override Java plugin defaults

sourceSets.main.output.classesDir = file("${project.webClassesDir}")

sourceSets.main.output.resourcesDir = file("${project.webClassesDir}")

configurations { gwt }

dependencies {

    compile project(":stocks4grab:s4g-common")

    //Java EE

    providedCompile "javax:javaee-api:7.0"

    //Others

    compile 'com.google.guava:guava:16.0.1'

    gwt 'com.google.guava:guava-gwt:16.0.1'

    //GWT

    compile fileTree (dir: gwt_sdk_root, includes:["gwt-servlet.jar"])

    //gwt fileTree (dir: gwt_sdk_root, includes: ["**/*.jar"])

    gwt fileTree (dir: gwt_sdk_root, includes: ["gwt-dev.jar", "gwt-user.jar", "validation-api*.jar"])

    //Errai

    //compile "org.jboss.errai:errai-bus:"+project.erraiVersion

    compile ("org.jboss.errai:errai-bus:"+project.erraiVersion){

        exclude group: 'com.google.guava'

    }

    compile "org.jboss.errai:errai-ioc:"+project.erraiVersion

    compile "org.jboss.errai:errai-cdi-client:"+project.erraiVersion

    //compile "org.jboss.errai:errai-jpa-datasync:"+project.erraiVersion

    compile ("org.jboss.errai:errai-jpa-datasync:"+project.erraiVersion){

        exclude group: 'com.google.guava'

    }

    compile "org.jboss.errai:errai-jaxrs-provider:"+project.erraiVersion

    compile "org.jboss.errai:errai-javax-enterprise:"+project.erraiVersion

    compile "org.jboss.errai:errai-weld-integration:"+project.erraiVersion

    compile "org.jboss.errai:errai-ui:"+project.erraiVersion

    //compile "org.jboss.errai:errai-navigation:"+project.erraiVersion

    compile ("org.jboss.errai:errai-navigation:"+project.erraiVersion){

        exclude group: 'com.google.guava'

    }

    //compile "org.jboss.errai:errai-cordova:"+project.erraiVersion

    //compile ("org.jboss.errai:errai-cordova:"+project.erraiVersion){

    //    exclude group: 'com.google.guava'

    //}

    //compile "org.jboss.errai:errai-jaxrs-client:"+project.erraiVersion

    compile ("org.jboss.errai:errai-jaxrs-client:"+project.erraiVersion){

        exclude group: 'com.google.guava'

    }

    compile "org.jboss.errai:errai-marshalling:"+project.erraiVersion

    compile "org.jboss.errai:errai-jboss-as-support:"+project.erraiVersion

}

task copyJars(type: Copy){

    from(configurations.compile) into("$project.webLibDir")

}

task copyWebapp(type: Copy){

    from("src/main/webapp") into("$project.warDir")

}

task compileGwt (type: JavaExec) {

   description = "Compile all gwt modules"

    //This prevents unnecessary GWT compilations!

   inputs.source sourceSets.main.java.srcDirs

   inputs.dir sourceSets.main.output.resourcesDir

   outputs.dir buildDir

   main = "com.google.gwt.dev.Compiler"

   classpath {[

            sourceSets.main.java.srcDirs,           // Java source

            sourceSets.main.output.resourcesDir,    // Generated resources

            sourceSets.main.output.classesDir,      // Generated classes

            sourceSets.main.compileClasspath,       // Dependencies

            configurations.gwt

   ]}

   args =

        [

            "com.peruncs.s4g.web.gwt.S4GWebApp", // Your GWT module(s)

            "-war", project.warDir,

            "-extra", project.gwtExtraDir,

            //"-logLevel", "INFO",

            "-strict",

            "-localWorkers", "2",

            "-compileReport",

            "-ea",

            "-optimize","9",

            // "-draftCompile" // Speeds up compilation by 25%

        ]

    maxHeapSize = "1024M"

}

task deployWarContent(type: Copy){

    from(project.warDir) into(project.deployedWarDir)

}

task deploy << {  

   ant.touch(file: "${project.deployedWarDir}.dodeploy")

}

task undeploy << {

    file(project.deployedWarDir).deleteDir()

    file("${project.deployedWarDir}.dodeploy").delete()

    file("${project.deployedWarDir}.deployed").delete()

}

//This would start the GWT code server

task startGwt << {

    description = "Launch GWT DevMode for all gwt modules"

    ant.java( spawn:true, fork:true, classname:"com.google.gwt.dev.DevMode"){

        jvmarg(value: "-DDEBUG") //Jetty debugging

        jvmarg(value: "-Djava.util.logging.config.file=${project.webInfDir}/logging.properties") //RestEasy logging

        jvmarg(value: "-Xmx1024m")

        jvmarg(value: "-Xss1024k")

        jvmarg(value: "-XX:PermSize=1024m")

        jvmarg(value: "-XX:MaxPermSize=1024m")

        jvmarg(value: "-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005")

        arg(value: "com.peruncs.s4g.web.gwt.S4GWebApp")

        arg(line: "-startupUrl index.jsp")

        //arg(line: "-startupUrl s4g-web/index.jsp")

        arg(line: "-war "+project.warDir)

        arg(line: "-noserver")

        arg(line: "-port 8080")

        arg(line: "-codeServerPort 9997")

        arg(line: "-extra "+ project.gwtExtraDir)

        arg(line: "-logLevel INFO")

        classpath {

            pathElement(location: "src/main/java")

            pathElement(location: "src/main/resources")

            pathElement(location: "${project.webClassesDir}")

            pathElement(path: configurations.gwt.asPath)

            pathElement(path: configurations.compile.asPath)

            pathElement(path: configurations.providedCompile.asPath)

        }

    }

}

task cleanWar << {

    delete project.warDir

}

//Tasks dependencies

compileJava.dependsOn copyWebapp, copyJars //upon java compilation, we copy all necessary files to have nice 'exploded' war

compileGwt.dependsOn classes

deploy.dependsOn classes, deployWarContent

war.dependsOn compileGwt

//Due to bugs: GRADLE-2171, GRADLE-1454 and GRADLE-1050,we resort to using Ant's zip task and avoid dupes in the war file

//TODO: revert back to the standard method, since the issue seems fixed as of Gradle 1.7

war << {

  ant.zip(destfile: project.war.archivePath,

            basedir: project.warDir ,duplicate: 'preserve',

            keepcompression: true, update: true)

}

eclipse {

wtp {

    facet {

      //you can add some extra wtp facets; mandatory keys: 'name', 'version':

      facet name: 'wst.jsdt.web', version: '1.0'

      facet name: 'jst.web', version: '3.0'

      facet name: 'jst.java', version: '1.7'

    }

  }

    //component {

    //    contextPath = '/'

    //}

   project {

      natures 'com.google.gwt.eclipse.core.gwtNature'

   }

}