Tiles rendering with blue background

Hello all,

I was doing some editing around the south west of Harpenden, Hertfordshire, UK yesterday and when I finished and updated the view in my browser the map was being rendered with a blue background rather than the usual beige.

Could anyone explain this for me? I’m hoping I didn’t cause the problem and as the area affected is large I’m assuming I can’t have done.

Many thanks,


Perhaps you made a self-intersection into coastline https://lists.openstreetmap.org/pipermail/talk/2014-August/070494.html. Another mail on the list told that the issue is already fixed.

Certainly a coastline problem, but given you were editing in Hertfordshire unlikely to be caused by you.

Coastline problems happen from time to time, and because they impinge on everyone editing in Britain they need to be hunted down quite quickly.

That’s what I was beginning to think. Thanks for confirming it - it was a bit alarming to suddenly see the area I’d been editing all turning blue!