Looking for logging into the Error User With This Already Exist site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Error User With This Already Exist site. After that you can login as usual with your login credentials.
https://stackoverflow.com/questions/40256032/sql-server-user-mapping-error-15023
https://ardalis.com/sql-server-error-user-group-or-role-already-exists-in-the-current-database
https://blog.sqlauthority.com/2007/02/15/sql-server-fix-error-15023-user-already-exists-in-current-database/
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/9faf79d0-f4b6-4b6c-9505-68cd2ec636af/the-login-already-has-an-account-under-a-different-user-name-microsoft-sql-server-error-15063?forum=sqlsecurity
https://dba.stackexchange.com/questions/35225/the-login-already-has-an-account-under-a-different-user-name
https://www.sqlservergeeks.com/sql-server-error-15023-user-already-exists-in-current-database/
https://www.linguee.com.br/ingles-portugues/traducao/username+already+exists!.html
https://www.linguee.com.br/ingles-portugues/traducao/user+already+exists.html
https://community.zuora.com/t5/Admin-Settings/quot-The-username-already-exists-Please-use-a-different-username/td-p/15472
https://portal.hostingcontroller.com/kb/a51/unable-to-create-user-error-user-already-exists.aspx
https://www.sqlservercentral.com/Forums/Topic277237-5-1.aspx
https://support.citrix.com/article/CTX205975
https://www.drupal.org/project/ldap_integration/issues/1694726