[keycloak-user] Uncaught server error: org.keycloak.models.ModelException: Could not find UserStorageProviderFactory

We recently noticed an exception in our keycloak 3.3.4 3-node cluster running in standalone HA mode: ESC[0mESC[31m14:10:28,640 ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-25) Uncaught server error: org.keycloak.models.ModelException: Could not find UserStorageProviderFactory for: MyUserStorage at org.keycloak.storage.UserStorageManager.getStorageProvider(UserStorageManager.java:164) at org.keycloak.storage.UserStorageManager.getUserById(UserStorageManager.java:370) at org.keycloak.storage.UserStorageManager.getUserByFederatedIdentity(UserStorageManager.java:422) at org.keycloak.models.cache.infinispan.UserCacheSession.getUserByFederatedIdentity(UserCacheSession.java:504) at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.importUserFromExternalIdentity(TokenEndpoint.java:894) at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.exchangeExternalToken(TokenEndpoint.java:857) at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.tokenExchange(TokenEndpoint.java:644) at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.processGrantRequest(TokenEndpoint.java:180) at sun.reflect.GeneratedMethodAccessor531.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) ..... Our UserStorageProvider was constructed based on the `EjbExampleUserStorageProvider` as described here: https://www.keycloak.org/docs/3.3/server_development/topics/providers.html, except for the following. The `EjbExampleUserStorageProvider` has these annotations: @Stateful While our UserStorageProvider has these annotations: @Stateful(passivationCapable=false) The `(passivationCapable=false)` was added to bypass an exception we hit when running this in HA mode. It was suggested by this thread: http://lists.jboss.org/pipermail/keycloak-user/2018-March/013442.html. There is a corresponding MyUserStorageProviderFactory class for this new MyUserStorageProvider. Things worked out fine until recently. From the stack trace above, it seems like the new MyUserStorageProviderFactory was removed from keycloakSession's keycloakSessionFactory. Does anyone know what might cause this? Thanks, Joy