id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
4200	Error header: Placeholder IDs must be unique for created elements.	osm@…	team	"POST http://www.openstreetmap.org/api/0.6/changeset/3402866/upload... Bad Request
Error header: Placeholder IDs must be unique for created elements.
org.openstreetmap.josm.io.OsmApiException: ResponseCode=400, Error Header=<Placeholder IDs must be unique for created elements.>
	at org.openstreetmap.josm.io.OsmApi.sendRequest(OsmApi.java:562)
	at org.openstreetmap.josm.io.OsmApi.sendRequest(OsmApi.java:462)
	at org.openstreetmap.josm.io.OsmApi.uploadDiff(OsmApi.java:423)
	at org.openstreetmap.josm.io.OsmServerWriter.uploadChangesAsDiffUpload(OsmServerWriter.java:116)
	at org.openstreetmap.josm.io.OsmServerWriter.uploadOsm(OsmServerWriter.java:163)
	at org.openstreetmap.josm.actions.UploadAction$UploadPrimitivesTask.realRun(UploadAction.java:588)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.doRealRun(PleaseWaitRunnable.java:62)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.run(PleaseWaitRunnable.java:116)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:636)

Ideally JOSM would ensure that the placeholder element IDs it tries to upload are unique.

(Manual methods for fixing the .osm also appreciated)."	defect	closed	normal		Core		worksforme