Class not found com.sun.xml.internal.ws.encoding.StringDataContentHandler ------------------------------------------------------------------------- Key: WFLY-12827 URL: https://issues.jboss.org/browse/WFLY-12827 Project: WildFly Issue Type: Bug Components: Mail Affects Versions: 18.0.1.Final Reporter: Dominik Derwiński Assignee: Yeray Borges Priority: Major Trying to send email I get: {noformat} [2019-11-26 03:10:04.781] [javax.activation] [EE-ManagedThreadFactory-default-Thread-18] [FINE ] [com.sun.activation.registries.LogSupport] [log] [43] : MailcapCommandMap: createDataContentHandler for text/plain [2019-11-26 03:10:04.781] [javax.activation] [EE-ManagedThreadFactory-default-Thread-18] [FINE ] [com.sun.activation.registries.LogSupport] [log] [43] : search DB #0 [2019-11-26 03:10:04.781] [javax.activation] [EE-ManagedThreadFactory-default-Thread-18] [FINE ] [com.sun.activation.registries.LogSupport] [log] [43] : got content-handler [2019-11-26 03:10:04.781] [javax.activation] [EE-ManagedThreadFactory-default-Thread-18] [FINE ] [com.sun.activation.registries.LogSupport] [log] [43] : class com.sun.xml.internal.ws.encoding.StringDataContentHandler [2019-11-26 03:10:04.781] [javax.activation] [EE-ManagedThreadFactory-default-Thread-18] [FINE ] [com.sun.activation.registries.LogSupport] [log] [49] : Can't load DCH com.sun.xml.internal.ws.encoding.StringDataContentHandler: java.lang.ClassNotFoundException: com.sun.xml.internal.ws.encoding.StringDataContentHandler from [Module "javax.activation.api" version 1.2.1 from local module loader @82de64a (finder: local module finder @659499f1 (roots: /u01/wildfly/wildfly18/modules,/u01/wildfly/wildfly18/modules/system/layers/base))] at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:255) at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:410) at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:398) at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:116) at java.base/java.lang.Class.forName0(Native Method) at java.base/java.lang.Class.forName(Class.java:315) at javax.activation.api@1.2.1//javax.activation.MailcapCommandMap.getDataContentHandler(MailcapCommandMap.java:598) at javax.activation.api@1.2.1//javax.activation.MailcapCommandMap.createDataContentHandler(MailcapCommandMap.java:555) at javax.activation.api@1.2.1//javax.activation.DataHandler.getDataContentHandler(DataHandler.java:600) at javax.activation.api@1.2.1//javax.activation.DataHandler.writeTo(DataHandler.java:299) at javax.mail.api@1.6.4//javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:316) at javax.mail.api@1.6.4//javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1551) at javax.mail.api@1.6.4//javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1148) at javax.mail.api@1.6.4//javax.mail.internet.MimeMultipart.updateHeaders(MimeMultipart.java:498) at javax.mail.api@1.6.4//javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1509) at javax.mail.api@1.6.4//javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2238) at javax.mail.api@1.6.4//javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2198) at javax.mail.api@1.6.4//javax.mail.Transport.send(Transport.java:99) {noformat} Maybe it's just missing module dependency for javax.mail.api, maybe you need to include JAXB and JAXWS libraries in WildFly modules for use on JDK 11+, when they were removed from JDK.