En Liferay 6.2, no arranca el servidor y en los logs muestra un error similar a este:
[ContextLoader:206] Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.liferay.portal.kernel.lar.ExportImportHelper' defined in class path resource [META-INF/util-spring.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.liferay.portal.lar.ExportImportHelperImpl]: Constructor threw exception; nested exception is java.lang.Error: Unresolved compilation problems: _ The import com.liferay.portal.lar.backgroundtask cannot be resolved_ The import com.liferay.portal.model.impl.LayoutImpl cannot be resolved_ The import com.liferay.portal.util.PropsValues cannot be resolved_ The import com.liferay.portal.util.WebKeys cannot be resolved_ StagingIndexingBackgroundTaskExecutor cannot be resolved to a type_ WebKeys cannot be resolved to a variable_ LayoutImpl cannot be resolved to a type_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ AlwaysCurrentUserIdStrategy cannot be resolved to a type_ CurrentUserIdStrategy cannot be resolved to a type_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ [Sanitized]
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.liferay.portal.kernel.lar.ExportImportHelper' defined in class path resource [META-INF/util-spring.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.liferay.portal.lar.ExportImportHelperImpl]: Constructor threw exception; nested exception is java.lang.Error: Unresolved compilation problems: _ The import com.liferay.portal.lar.backgroundtask cannot be resolved_ The import com.liferay.portal.model.impl.LayoutImpl cannot be resolved_ The import com.liferay.portal.util.PropsValues cannot be resolved_ The import com.liferay.portal.util.WebKeys cannot be resolved_ StagingIndexingBackgroundTaskExecutor cannot be resolved to a type_ WebKeys cannot be resolved to a variable_ LayoutImpl cannot be resolved to a type_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ AlwaysCurrentUserIdStrategy cannot be resolved to a type_ CurrentUserIdStrategy cannot be resolved to a type_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ PropsValues cannot be resolved to a variable_ [Sanitized]
En este caso el error se solucionó des-instalando el plugin-ext y volviendo a desplegarlo en el arranque.
