Can anyone help with an error message I am getting on dm’s

[Secondstart1001]

Will keep this brief. Another poster contacted me via dm’s for some help and support and I was happy to do this. We messaged a lot and now when I message I get error 500 …. It’s not happening with any of my other DM’s .. I feel like I need someone to tell me I’ve been blocked but have no idea why .:

That happens when they have deleted their account.

It won’t happen if you’re blocked; your message still looks like it’s been sent; they just won’t receive it.

They have been in touch, they deleted old account.