java.lang.LinkageError: loader constraint violation:previously initiated loading for a different type with name "javax/mail/Session"

Question

I am getting the following error when I try to send email using javax.mail-api:

Caused by: java.lang.LinkageError: loader constraint violation: loader (instance of org/apache/felix/framework/BundleWiringImpl$BundleClassLoaderJava5) previously initiated loading for a different type with name "javax/mail/Session"
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2279)
        at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1501)
        at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:75)
        at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1955)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at com.sun.mail.util.PropUtil.getBooleanSessionProperty(PropUtil.java:86)
        at javax.mail.internet.MimeMessage.initStrict(MimeMessage.java:320)
        at javax.mail.internet.MimeMessage.<init>(MimeMessage.java:195)
        at sendEmail(manage.java:216)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.camel.component.bean.MethodInfo.invoke(MethodInfo.java:408)
        at org.apache.camel.component.bean.MethodInfo$1.doProceed(MethodInfo.java:279)
        at org.apache.camel.component.bean.MethodInfo$1.proceed(MethodInfo.java:252)

Code:

Public void sendEmail() {
    String to = "[email protected]";
    String from = "[email protected]";
    final String username = "[email protected]";
    final String password = "password";
    Properties properties = new Properties();
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable", "true");
    properties.put("mail.smtp.host", "smtp.office365.com");
    properties.put("mail.smtp.port", "587");
    Session session = Session.getInstance(properties, new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(username, password);
        }
    });
    try {
        System.out.println("Inside test");
        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
        message.setSubject("Testing Subject");
        message.setText("This is message body");
        Transport.send(message);
        System.out.println("Sent message successfully....");
     } catch (MessagingException e) {
         throw new RuntimeException(e);
     }
}

My maven dependency:

<dependency>
    <groupId>javax.mail</groupId>
    <artifactId>javax.mail-api</artifactId>
    <version>1.5.5</version>
</dependency>

Please help.

Solution

As suggested in comments, add your dependency to javamail as provided dependency:

<dependency>
        <groupId>com.sun.mail</groupId>
        <artifactId>javax.mail</artifactId>
        <version>1.5.1</version>
        <scope>provided</scope>
</dependency>

This will skip adding duplicate jars which would then be loaded by different classloaders.

If not somehow forced to use old version of javamail you should update to latest which is currently

<dependency>
        <groupId>com.sun.mail</groupId>
        <artifactId>javax.mail</artifactId>
        <version>1.5.5</version>
        <scope>provided</scope>
</dependency>

Comments

[Jan]

Check all yout jars. You probably have another mail.jar (not -api) sitting around. If thats the case mark mail-api jar "provided" to skip packaging that

[Ralf]

Are you using plain vanilla Felix as the runtime? Or a container like Karaf? Your code works for me in Karaf 4, using javax.mail instead of javax.mail-api as a bundle dependency. As Jan already mentioned, somehow you end up with two versions on your bundle classpath.

[user2782405]

@Jan: I tried adding "provided" but I am getting same error.

[Jan]

Check your classpath - for everything mail-* and make sure it's all in server libs or application libs but not mixed

[user2782405]

@Ralf: I am using karaf as well (version 3.0.4). Can you please share your dependency code. I tried but my project fails to build without javax.mail-api.

[heenenee]

@user2782405 You should put your solution in an answer and accept it.

[Bill Shannon]

As described on the JavaMail project page, the javax.mail-api artifact is only for compiling against and includes only the standard javax.mail API definitions. The javax.mail artifact includes the entire runtime library.

[Bill Shannon]

You probably want to use the current version - 1.5.5.

[user2782405]

@BillShannon: I tried with version 1.5.5 but I am getting same error.

[Bill Shannon]

I don't understand. I thought when you said "I used different Maven dependency and it worked" it meant that you had solved the problem. If not, please describe exactly what you're doing now and exactly what error you're getting. If your solution works with version 1.5.1 but fails with version 1.5.5, please tell me more.

[Jan]

@BillShannon The way I understood the issue, there were conflicting javamail versions somewhere in the runtime environment. Adding 1.5.5 might still lead to duplicate versions (1.5.1 in runtime, 1.5.5 from dependency)

[Bill Shannon]

Well, with "provided" scope, you're getting the version that comes with the runtime you're using. If your runtime comes with 1.5.1, then you're right that you should use 1.5.1 in your dependency. With "provided" scope, you're not going to end up with two versions, you're only going to get the version that's in the runtime, not the version you mention in the dependency. Ideally, your dependency should mention the same version that your runtime provides.

[Jan]

@BillShannon user claims to have tried that and failed (see comments)

[Bill Shannon]

As I understood it, user tried that without "provided" scope, and with changing the version, and that failed. As expected. The version isn't the solution to the original problem, "provided" scope is. But in general, given a choice, user should use the latest version, not some older version.

[Jan]

@BillShannon I agree - check the comments on the question - third comment, directed at me: "I tried adding "provided" but I am getting same error. I'll edit the answer nontheless.

[Bill Shannon]

Never mind. It looks like the question was edited to remove that text. If "provided" doesn't work, I have no idea what's wrong.

[user2782405]

@BillShannon and Jan: Sorry for the delay. I tried using version 1.5.5 with and without "provided" but it didn't work. I was getting same error as before (loader constraint violation). When I changed the version to 1.5.1 then it worked. I don't know why.

[Bill Shannon]

The "loader constraint violation" means you have two copies of the JavaMail classes available to your application. When using "provided" scope, the JavaMail jar file is not included with your application, so there's no way it can be the source of the problem. Unless you have another dependency that also includes the javax.mail classes. What are the other dependencies?

[user2782405]

<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-core</artifactId> <version>${camel-version}</version> </dependency><dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-blueprint</artifactId> <version>${camel-version}</version> </dependency> <dependency> <groupId>org.codehaus.jackson</groupId> <artifactId>jackson-mapper-asl</artifactId> <version>1.6.4</version> <scope>compile</scope> </dependency>