No idea - is it in a pot or the ground? Has the whole thing drooped and gone floppy, or just some stems? Which Euphorbia is it?

It is in the ground in the border and all the stems have gone floppy. Can't remember which one it is.....but similar to wulfenii...might even be that!

One variety I have has done the same, mainly on the newer stems. Whilst another variety next to it has not changed at all. It did this last year & was fine within a few weeks.