This task must be called by the create script. ${ext.name}-ext already exists. . Usage: ant upgrade-ext -Dext.dir=C:\ext -Dext.name=hello-world -Dext.display.name="Hello World" The arguments "ext.dir", "ext.name", and "ext.display.name" are not properly specified. This task will build an EXT plugin from a legacy EXT environment. The files in the directory denoted by "ext.dir" will be copied into the EXT plugin directory called "ext.name"-ext. The property "ext.dir" must point to a legacy EXT environment and the EXT plugin directory called "ext-name"-ext must not already exist. ${ext.name}-ext already exists.