why does this tumblr url say not found when its being used?

[Rq.]

alright, so, im trying to make a new blog. i type in the url and it says its taken, but when i go to look for the actual blog, it says "not found." is there a reason for this?

[Sadsongs]

It may have been previously used for spam or porn.

[Forever94]

It could be a couple of reasons:
1. Someone is using the code from the "not found" page as a placeholder.
2. It could have been a previously problematic account
3. someone could have JUST deleted their account with that name.