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Grails hip tip: LinkageError with SAXParseException

Posted by: Andrew Glover on 06/10/2010

Recently a bogue error popped up with an existing Grails project at a client site. In an effort to abstract core domain logic (i.e. business rules) for a financial application, we decided to leverage Drools; consequently, after some prototyping of rules in a non-Grails project, we decided to start evaluating the Grails Drools plugin.

After installing said plugin, however, Grails failed to start up, instead issuing the error:

java.lang.LinkageError: loader constraint violation: loader (instance of ) previously initiated loading for a different type with name “org/xml/sax/SAXParseException”

followed by an equally nefarious stack trace.

It turns out that differing versions of the xml-apis jar will force this issue; accordingly, if this happens to you, you can fix the situation by simply locating the offending jar file (in this case, it was the Drools plugin which includes a differing version: xml-apis-1.0.b2.jar) and removing it.

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Andrew Glover's complete blog can be found at: http://thediscoblog.com/

About Andrew Glover

Andrew is the founder of the easyb BDD framework and the co-author of Addison Wesley's "Continuous Integration", Manning's "Groovy in Action" and "Java Testing Patterns". He is an author for multiple online publications including IBM's developerWorks and Oreilly's ONJava and ONLamp portals. He actively blogs about software at thediscoblog.com.

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