id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
18915	"""Precondition violation"" not fixable from within JOSM"	Geimas5	team	"Recently, I have occasionally started to receive errors while uploading data with no apparent way of solving the error without starting over.

What happens:
I receive this error when attempting to upload:

Uploading to the server failed because your current dataset violates a precondition. The error message is: ResponseCode=412, Error Header=<Precondition failed: Relation 10810290 requires the ways with id in 779691669, which either do not exist, or are not visible.>

It does not help to download the area again to the same layer, and the only way I have found to fix the problem it to discard all changes by deleting the data layer and start over.

"	defect	closed	normal	20.05	Core		fixed	upload conflict	simon04