It is a mystery. I edit an area in Germany and JOSM reported an error with a node in US. JOSM reported that the node was not correctly connected with a line. I called both object ID's and removed the node from the line. Otherwise I had to discard more than 100 entries of my work. I'm not able to solve that problem in an other way.
If you want you can explain me, how I can save a changeset, redo it, change it and upload the edited change set. I found no explanation in German Wiki for this procedure.
Update: Now I have found a way to do this. But I saw you have corrected the point already. I would do the same. So all things are fine. Thanks for the comment.

Your comment ist OK and clear. But during my editing in Germany I got an error message from a object in US. I work with JOSM and I'm sure that I didn't made any changes in US. To save my changes I must clear the reported error in US. May be there ist any bug in the software.

Dieser Änderungssatz ist falsch. Bitte gelöschte Halle wiederherstellen und die abgerissenen Garagen löschen.