Hi there, getting kinda desperate here... I wrote a custom form authenticator that extends the UsernamePasswordForm of Keycloak and packaged it up in an EJB jar inside an EAR file (almost identical to the official example <https://github.com/keycloak/keycloak/tree/master/examples/providers/authe...>). I can configure it in the authentication flow but as soon as it is loaded as part of an auth flow I get " Failed to define class org/keycloak/authentication/authenticators/browser/UsernamePasswordForm " error. I have another authenticator in the same package that does *not *extend org.keycloak.authentication.authenticators.browser.UsernamePasswordForm and it loads and executes fine. I tried adding the module keycloak-services explicitly to my EJB jars deployment descriptor: <?xml version="1.0" encoding="UTF-8"?> <jboss-deployment-structure> <deployment> <dependencies> <module name="org.keycloak.keycloak-services" slot="main" /> </dependencies> </deployment> </jboss-deployment-structure> No avail. Looks like something wrong with the way Keycloak accesses the classes discovered by ServiceLoader. Anyone got any hints or seen this before? Many thanks Niels Full stack trace: 23:13:01,107 WARN [org.jboss.modules] (default task-44) Failed to define class my.sso.plugins.authentication.authenticators.browser.CustomUsernamePasswordForm in Module "deployment.custom-keycloak-extension-archive.ear.custom-user-federation-ejb.jar" from Service Module Loader: java.lang.NoClassDefFoundError: Failed to link my/sso/plugins/authentication/authenticators/browser/CustomUsernamePasswordForm (Module "deployment.custom-keycloak-extension-archive.ear.custom-user-federation-ejb.jar" from Service Module Loader): org/keycloak/authentication/ authenticators/browser/UsernamePasswordForm at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance( NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance( DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at org.jboss.modules.ModuleClassLoader.defineClass( ModuleClassLoader.java:446) at org.jboss.modules.ModuleClassLoader.loadClassLocal( ModuleClassLoader.java:274) at org.jboss.modules.ModuleClassLoader$1.loadClassLocal( ModuleClassLoader.java:77) at org.jboss.modules.Module.loadModuleClass(Module.java:713) at org.jboss.modules.ModuleClassLoader.findClass( ModuleClassLoader.java:190) at org.jboss.modules.ConcurrentClassLoader. performLoadClassUnchecked(ConcurrentClassLoader.java:412) at org.jboss.modules.ConcurrentClassLoader.performLoadClass( ConcurrentClassLoader.java:400) at org.jboss.modules.ConcurrentClassLoader.loadClass( ConcurrentClassLoader.java:116) at my.sso.plugins.authentication.authenticators.browser. CustomUsernamePasswordFormFactory.create(CustomUsernamePasswordFormFact ory.java:56) at my.sso.plugins.authentication.authenticators.browser. CustomUsernamePasswordFormFactory.create(CustomUsernamePasswordFormFact ory.java:16) at org.keycloak.authentication.DefaultAuthenticationFlow. processFlow(DefaultAuthenticationFlow.java:164) at org.keycloak.authentication.DefaultAuthenticationFlow. processFlow(DefaultAuthenticationFlow.java:127) at org.keycloak.authentication.AuthenticationProcessor. authenticateOnly(AuthenticationProcessor.java:853) at org.keycloak.authentication.AuthenticationProcessor. authenticate(AuthenticationProcessor.java:722) at org.keycloak.protocol.AuthorizationEndpointBase. handleBrowserAuthenticationRequest(AuthorizationEndpointBase.java:145) at org.keycloak.protocol.oidc.endpoints.AuthorizationEndpoint. buildAuthorizationCodeAuthorizationResponse(AuthorizationEndpoint.java: 395) at org.keycloak.protocol.oidc.endpoints. AuthorizationEndpoint.build(AuthorizationEndpoint.java:139) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke( NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke( DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.jboss.resteasy.core.MethodInjectorImpl.invoke( MethodInjectorImpl.java:140) at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget( ResourceMethodInvoker.java:295) at org.jboss.resteasy.core.ResourceMethodInvoker.invoke( ResourceMethodInvoker.java:249) at org.jboss.resteasy.core.ResourceLocatorInvoker. invokeOnTargetObject(ResourceLocatorInvoker.java:138) at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke( ResourceLocatorInvoker.java:107) at org.jboss.resteasy.core.ResourceLocatorInvoker. invokeOnTargetObject(ResourceLocatorInvoker.java:133) at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke( ResourceLocatorInvoker.java:101) at org.jboss.resteasy.core.SynchronousDispatcher.invoke( SynchronousDispatcher.java:406) at org.jboss.resteasy.core.SynchronousDispatcher.invoke( SynchronousDispatcher.java:213) at org.jboss.resteasy.plugins.server.servlet. ServletContainerDispatcher.service(ServletContainerDispatcher.java:228) at org.jboss.resteasy.plugins.server.servlet. HttpServletDispatcher.service(HttpServletDispatcher.java:56) at org.jboss.resteasy.plugins.server.servlet. HttpServletDispatcher.service(HttpServletDispatcher.java:51) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at io.undertow.servlet.handlers.ServletHandler.handleRequest( ServletHandler.java:85) at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl. doFilter(FilterHandler.java:129) at org.keycloak.services.filters.KeycloakSessionServletFilter. doFilter(KeycloakSessionServletFilter.java:90) at io.undertow.servlet.core.ManagedFilter.doFilter( ManagedFilter.java:61) at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl. doFilter(FilterHandler.java:131) at io.undertow.servlet.handlers.FilterHandler.handleRequest( FilterHandler.java:84) at io.undertow.servlet.handlers.security. ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler. java:62) at io.undertow.servlet.handlers.ServletDispatchingHandler. handleRequest(ServletDispatchingHandler.java:36) at org.wildfly.extension.undertow.security. SecurityContextAssociationHandler.handleRequest( SecurityContextAssociationHandler.java:78) at io.undertow.server.handlers.PredicateHandler.handleRequest( PredicateHandler.java:43) at io.undertow.servlet.handlers.security. SSLInformationAssociationHandler.handleRequest( SSLInformationAssociationHandler.java:131) at io.undertow.servlet.handlers.security. ServletAuthenticationCallHandler.handleRequest( ServletAuthenticationCallHandler.java:57) at io.undertow.server.handlers.PredicateHandler.handleRequest( PredicateHandler.java:43) at io.undertow.security.handlers.AbstractConfidentialityHandler .handleRequest(AbstractConfidentialityHandler.java:46) at io.undertow.servlet.handlers.security. ServletConfidentialityConstraintHandler.handleRequest( ServletConfidentialityConstraintHandler.java:64) at io.undertow.security.handlers.AuthenticationMechanismsHandle r.handleRequest(AuthenticationMechanismsHandler.java:60) at io.undertow.servlet.handlers.security. CachedAuthenticatedSessionHandler.handleRequest( CachedAuthenticatedSessionHandler.java:77) at io.undertow.security.handlers.NotificationReceiverHandler. handleRequest(NotificationReceiverHandler.java:50) at io.undertow.security.handlers.AbstractSecurityContextAssocia tionHandler.handleRequest(AbstractSecurityContextAssocia tionHandler.java:43) at io.undertow.server.handlers.PredicateHandler.handleRequest( PredicateHandler.java:43) at org.wildfly.extension.undertow.security.jacc. JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61) at io.undertow.server.handlers.PredicateHandler.handleRequest( PredicateHandler.java:43) at org.wildfly.extension.undertow.deployment. GlobalRequestControllerHandler.handleRequest( GlobalRequestControllerHandler.java:68) at io.undertow.server.handlers.PredicateHandler.handleRequest( PredicateHandler.java:43) at io.undertow.servlet.handlers.ServletInitialHandler. handleFirstRequest(ServletInitialHandler.java:292) at io.undertow.servlet.handlers.ServletInitialHandler.access$ 100(ServletInitialHandler.java:81) at io.undertow.servlet.handlers.ServletInitialHandler$2.call( ServletInitialHandler.java:138) at io.undertow.servlet.handlers.ServletInitialHandler$2.call( ServletInitialHandler.java:135) at io.undertow.servlet.core.ServletRequestContextThreadSet upAction$1.call(ServletRequestContextThreadSetupAction.java:48) at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call( ContextClassLoaderSetupAction.java:43) at org.wildfly.extension.undertow.security. SecurityContextThreadSetupAction.lambda$create$0( SecurityContextThreadSetupAction.java:105) at org.wildfly.extension.undertow.deployment. UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0( UndertowDeploymentInfoService.java:1508) at org.wildfly.extension.undertow.deployment. UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0( UndertowDeploymentInfoService.java:1508) at org.wildfly.extension.undertow.deployment. UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0( UndertowDeploymentInfoService.java:1508) at org.wildfly.extension.undertow.deployment. UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0( UndertowDeploymentInfoService.java:1508) at io.undertow.servlet.handlers.ServletInitialHandler. dispatchRequest(ServletInitialHandler.java:272) at io.undertow.servlet.handlers.ServletInitialHandler.access$ 000(ServletInitialHandler.java:81) at io.undertow.servlet.handlers.ServletInitialHandler$1. handleRequest(ServletInitialHandler.java:104) at io.undertow.server.Connectors.executeRootHandler(Connectors. java:326) at io.undertow.server.HttpServerExchange$1.run( HttpServerExchange.java:812) at java.util.concurrent.ThreadPoolExecutor.runWorker( ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run( ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)