I have reported the issue Jaymac mentions. As John says, resetting the link by doing a search may well clear the problem.
These days, browsers seem to hold more information than we realise with logins, cookies and caches and it's not always helpful.
Colin
Here is an extract from the FAQ section.
I can’t remember or don’t know my username!
Don’t worry, you can log in with either your username or email address.
I don’t know my password!
Don’t worry, you can reset your password here, enter your email address and a password reset email will be sent to you. Don’t forget to check your Spam or Junk folder for this email.
Why can’t I change my username?
Once a username has been set this can’t be changed. If your username has been migrated over from our old forum (pre-September 2023) this may have changed due to incompatible characters on the new system.
Why won’t the registration form accept my username/password?
Usernames must be lowercase letters and numbers only. Capital letters, spaces and special characters are not allowed.
Passwords should be at least 10 characters containing a mix of letters, numbers, capitals, and special characters (@, #, *, etc.), some special characters are not allowed such as a backslash ( \ ).