Mint plant turning black?

Hi, I swear I saw a similar post on here but I can not find it so sorry to post the same sort of topic again.
But my mint plant is turning black it is potted in a sunny position and well watered but the leaves are turning black does anyone know why?

Mint is a drought plant and the watering is creating boggy conditions for it. Water only when you see it a bit droopy which might happen with potted plants versus ground plants. If you let this plant dry out for a while and it still doesn't recover, try potting it in some fresh soil, water once, and then only on occasion.

I always thought it was just about impossible to kill mint, it always seems so rampant. You learn something every day

I thought mint was hard to kill too, but I seem to have a good nac of doing these things Im still on that very steep learning curve (climb) ha, but the mint has lived to see another day! I have re-potted and only dampened the new soil slightly and its already alot better Thank you x

I don't know why but I have never been successful with mint in pots.  they don't even do well when you plant them in pots and sink them in the ground like you are advised to do to contain the roots.  But put them straight in the ground and they romp away and become so invasive you wish you hadn't bothered.  If someone has the magic answer I would love to hear it!