Since a few EAP's back, it is no longer possible to run an incremental build when generating ear files. When you have a project which contains more than one war file, a full rebuild will create a correct ear file, however when a change is made to a jsp file followed by a make operation, the ear file will delete the other war's only leaving the war that contains the recently changed file. Another incremental rebuild will again add the missing war files, but delete the one that was in the ear file already. Further incremental builds will swap between the sets of war files. The only way to get back to a fully working ear is to do a full build again.