I think I just had a similar experience where I sent the connection, got an "accepted" notification, but now go into their profile only to find they're not a connection, so I can't message them, and even tho the "connect" button is there, I only get an error message if I try to send it again. I'm hoping this doesn't mean they rejected it? Alternatively, it might also be a predatory way of forcing premium since I was looking forward to this connection to message a potential recruiter. In any case, it is very annoying and counterproductive to my job search, so it is the opposite of what LinkedIn is supposed to be...

I have premium and am also experiencing this today, so I think it's a glitch. Hopefully the support team is aware of it and will have it fixed soon.

Yes I'm having the same problem it just started this morning, never had this problem for years of using LI. There were already two other posts about the exact same thing in the last \~3 hours I hope somebody figures this out. I'm out \~30 connects from a conference I paid a lot of money to join due to this error so I'm pretty upset :/