"No exception of type SomeException can be thrown; an Exception type must be a subclass of Throwable" in JBDS

Solution Verified - Updated -


  • JBoss Developer Studio (JBDS) 2.0


The EJB use apache email to send email, so I included the apache_common_mail.jar as referenced libraries in the Inventory EJB project.

JBDS shows the error: No exception of type EmailException can be thrown; an Exception type must be a subclass of Throwable


Add commons-lang.jar to the project's build path.

Root Cause

Apache commons-mail depends on commons-lang, and has an exception class derived from commons-lang's NestedRuntimeException class. That jar was missing from the project's build path, so JBDS couldn't process the class heirarchy and it reports the somewhat confusing error that the exception isn't derived from Throwable.

Diagnostic Steps

Check whether there is the error "org.apache.commons.lang.exception.NestableException cannot be resolved, it is indirectly referenced from a required .class file" reported at the top of the file.

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