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Editorial Team
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Asked: 2026-05-11T21:51:25+00:00

I run iPlanet’s Java application server, something in it is loading commons-logging-1.0.4.jar . That’s

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I run iPlanet’s Java application server, something in it is loading commons-logging-1.0.4.jar.

That’s fine until one of my applications calls AuthSSLProtocolSocketFactory which is another apache library that also uses commons-logging.

I put the jar on the jvm classpath and get this error:

Invalid class loader hierarchy. You have more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed.
(Caused by org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy....

It seems that commons-logger doesn’t like having two instances of itself loaded in different classloaders. I assume the application server has its own classloader that’s loading it the first time (Although I can’t find any appserver configuration that mentions it) so when my application goes to load it a second time it throws that exception.

I can’t change the web server, and I can’t change the apache library. Suggestions?

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1 Answer

  1. Editorial Team

    Are you putting commons logging in your classpath explicitly? You said jvm classpath, so I assume you are specifying it on the command line when you start iPlanet. That’s not the recommended way to load jars in J2EE apps.

    The easiest thing is to just let the Apache library use the commons logging jar that comes with iPlanet. Don’t put commons-logging.jar in your WEB-INF/lib dir or in any classpath setting and the iPlanet one should be picked up automatically.

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