Could you check your startup ouput and search for websession to see if it says where the second one is from?
Do you define or modify a websession component in the components.xml?
Something must be providing or configuring a second one.
i got the same problem when created seam ear project from eclipse Ganymede, using seam web project the problem was that generator made an entry in MANIFEST.MF of projectName-jar project. I removed it from there, added jboss-seam.jar to classpath. Then it deployed ok.
Had the very same error, without duplicate seam.jar and of course also without anything defined in the components.xml that only roughly resembles a webSession. Narrowed it down to a version-problem between two independent .wars: The one ran seam2.2.2.EAP, the other one ran 2.0.2.GA: The second one only produces this error when it is deployed after the first (saw this when I rebooted the server and the error suddenly gone). Upgrading the second one two 2.2.2.EAP5 gets rid of the error completely.
Two rules of thumb:
- Never ever upgrade seam, once you got it running.
- If you absolutely have to violate the first rule, make sure that you run the same version in all your apps.
Still totally puzzled why this happened - the apps should have been isolated, but appearantly, they are not...
Multiple Wars was a problem because some components clash if there are multiple instances.
For multiple war, use Seam 2.2, which solved this problem.
I totally disagree with Stefan Frank. I'm running about 4-5 applications on the same JBoss AS instance every app has different version of seam. There are no problems.
Also I have never had problems with upgrading applications to newer Seam version (within same major version :) ).
If you are deploying your project as a EAR project, in Add and Remove menu of JBoss AS in your IDE, don´t add jboss-seam.jar to configure resources. This library is already included in EAR file.
I have solved the problem this way.