I tried to sign up on stackoverflow.com from this url : How to avoid "ls: write error: Broken pipe" with php exec
I clicked on "sign up" on top, then "click here to sign up".
I wrote my infos and clicked on "Create stack exchange account".
I then arrived on a page telling me "wrong link" or something like this (very sorry, I closed the window), and giving no info about my account creation. The account was not created, I didn't receive a mail, I couldn't log in.
The message was quoting the url I was coming from.
Then I went on the site's homepage, clicked "sign up", etc, and the account creation worked perfectly.
I used the same login and mail and it worked, so it show again the 1st try didn't work (I think).
Looks like this bug has returned: 404 Error on page redirection after creating an account - slashes in URL escaped