Is my cactus/euphorbia dying?

marc.a.chapman

I’ve just noticed this area on black on one of the tips of my cactus (although I believe from looking online it’s actually a euphorbia). The dried, brown bit top right was there when I bought it over a year ago, but the black bit around it is definitely new. Does it mean that it’s dying? Is there anything I can do to save it? Any help would be appreciated!

hogweed

Brown bit on cacti and succulents usually means that it has been overwatered and possibly not in enough light and/or possibly not in the right compost/pot. What are your growing conditions like?