There was a bug in the framework. The usernames, called handles in the framework, are stored in the database as entered by the user. So your original name became handle = "AliTaghavi(Math)" there. To be used as URL by the browser, spaces are converted to '+' characters and other characters by their HTML Unicode substitutes, so there, your name was translated to "AliTaghavi%2528Math%2529". When calling the subpages of the profile page, this name was not converted back, so that this handle couldn't be found in the database. Therefore, the page was also marked as "not found".
I was able to fix this bug for spaces (translated as '+') but not for all Unicode substitutes. So please avoid these characters in usernames. Thank you.
This bug existed in the original framework already since the beginning of the site, and no one noticed it.