Skip navigation.
Downloads | Product Documentation | Support

WebLogic Server Frequently Asked Questions

# FAQs: Upgrading

- What is Compatibility mode?
- How do I run WebLogic Server 8.1 in Compatibility mode when upgrading?
- What is two-phase deployment?
- Why do I keep getting a NoSuchMethodError when running an application on WebLogic Server 8.1?

Q. What is Compatibility mode?

A. When you upgrade to WebLogic Server 8.1 from previous versions of WebLogic Server, Compatibility mode allows you to keep your old configuration of users, groups, and ACLs.

Q. How do I run WebLogic Server 8.1 in Compatibility mode when upgrading?

A. WebLogic Server 8.1 recognizes your old config.xml file and automatically runs in Compatibility mode.

Q. What is two-phase deployment?

A. WebLogic Server 8.1 uses two-phase deployment. Previous to WebLogic Server 7.0, when you deployed an application, a copy of the application file(s) was sent to all the targeted servers, which in turn, loaded the application. If any of those servers failed (or partially failed), the deployment was placed in an inconsistent state.

In the current release of WebLogic Server, the application is first prepared across the servers and then activated in a separate phase. In the prepare phase, the application is prepared for deployment without allowing user requests to the application. When the servers are ready, the application is activated everywhere. With this model, it is still possible to have a failure occur during the activation phase, which leads to the inconsistent state, but it is much less likely to occur.

For more information on this deployment model and other 8.1 deployment features, see WebLogic Server Application Deployment.

Q. Why do I keep getting a NoSuchMethodError when running an application on WebLogic Server 8.1?

A. Make sure that you are not running the server with a patch for a previous version of WebLogic Server. For exact information of a particular patch, contact Customer Support.

Also make sure that you do not have any JAR files in your server `CLASSPATH` that conflict with the version of J2EE that is supported by WebLogic Server 8.1, J2EE version 1.3. The 1.3 version of J2EE is added to the WebLogic Server 8.1 `CLASSPATH` by default. For example, you may have to remove `j2ee12.jar` from your server `CLASSPATH`.