I always teach my customers to tackle the first error that is reported. This is the first error that is reported when I try to deploy my web application:
17 persistenceUnit WARN [localhost-startStop-1] openjpa.Runtime - An error occurred while registering a ClassTransformer with PersistenceUnitInfo: name 'persistenceUnit', root URL [file:/var/lib/tomcat8/webapps/ROOT/WEB-INF/classes]. The error has been consumed. To see it, set your openjpa.Runtime log level to TRACE. Load-time class transformation will not be available.
Part of the message says "The error has been consumed." What does that mean? Does that mean the error is important? Or not important?
(You'll be pleased to hear that it is not web-programming that I teach.)