The listener "com.sun.faces.config.ConfigureListener" is already configured for this context. Duplicate definition was ignored

Question

I get the following information when the application starts:

The listener "com.sun.faces.config.ConfigureListener" is already configured for this context. The duplicate definition has been ignored. 

and I want to know what is the reason for this error?

Answer 1

First of all, this is a warning , not an error . The difference is quite huge. The web application may just continue to work. Warnings are simply to inform the developer of circumstances that differ from expected / natural behavior that does not necessarily impair functionality. This is very useful when the developer was not aware of the configuration and / or its consequences.

This listener is usually automatically registered by the JSF TLD file and ServletContainerInitializer . You may receive this warning message if you actually registered the same listener in your web.xml web application.

This warning is not harmful. Basically, you are informed that you do not need to explicitly register a listener in your webapp web.xml for a specific target servlet container. You can safely remove the <listener> entry in question from webapp web.xml .

However, explicit registration is mandatory in some cases, for example, when the webapp intends to deploy to a servlet buggy container that does not load the listener correctly from the TLD and / or does not support ServletContainerInitializer .

See also:

• could not find Factory: javax.faces.context.FacesContextFactory