Re: [keycloak-user] NotSerializableException: org.keycloak.adapters.elytron.ElytronAccount

I've installed the keycloak-wildfly-adapter-dist-4.6.0.Final.zip adapter in a clean version of WildFly Full 14.0.1.Final, running on Windows 8.1. The keycloak server is running on a separate port. When I configure the adapter subsystem (server not running) with the newer Elytron adapter using > cd bin > jboss-cli.bat --file=adapter-elytron-install-offline.cli -Dserver.config=standalone-full.xml and thereafter attempt to sign into a basic war application I get the keycloak login page, followed by an error page once credentials are posted. The server.log reports the following (abbreviated) error stacktrace 2018-11-21 20:17:37,654 ERROR [io.undertow.request] (default task-1) UT005023: Exception handling request to /curo-crm/: java.lang.IllegalArgumentException: org.infinispan.commons.marshall.NotSerializableException: org.keycloak.adapters.elytron.ElytronAccount at org.wildfly.clustering.web.infinispan.session.coarse.CoarseSessionAttributes.setAttribute(CoarseSessionAttributes.java:71) [snip] Caused by: org.infinispan.commons.marshall.NotSerializableException: org.keycloak.adapters.elytron.ElytronAccount Now, if I configure the adapter subsystem with the legacy non-Elytron adapter on WildFly using > cd bin > jboss-cli.bat --file=adapter-install-offline.cli -Dserver.config=standalone-full.xml everything works without errors i.e. I can access the protected web app on login success. Question 1: Have I missed something in the server configuration that is causing the NotSerializableException? Question 2: The keycloak config documentation recommends the use of the newer Elytron adapter over the legacy non-Elytron adapter, but gives no reasoning. Are there drawbacks to using the legacy version? Thanks