Wont let me blacklist?

This is usually caused by a copy and paste of a membername that has an extra space before or after it, or a misspelling or missing char, or the more common case the member is already on your list.

Sometimes people have a _ before or after or in the middle of their membername which can be hidden on some views of their membername depending on where you are seeing it. I just added your membername ok to mine, then removed it ok. Good to double check membername and how you are entering eg manually writing it in or copy/paste.

We have been asking Trademe for years to add more meaningful error messages like there used to be on the old site, rather than the general server error message which then gives you a mystery guessing game like this.

Hi, thanks for the prompt reply. I tried adding my username to my blacklist and gor the same reply,   "oops....etc.". 

Yes, you would, as you can't blacklist yourself. Try adding mine.

Hi, sme response when trying to add your name? Thanks for the help.

Not really any other ideas other than the usual, try a different browser, clear your cache, log out then back in, etc.

Success! Logged in with Edge instead of my usual Chrome and it accepted the addition. Thanks for the great tech support.

Good one. Glad something there sorted it for you.