This is weird. I don't know what is problem on my website. My website works on local server but not on live server. Login page works on first signin but after logout then re-login again message says: "invalid username and password" since it works on first attempt. I found out when I debugging that http://xxxxx.com/api/authentication/sign not found. It display 404 page not found. Sometimes you can login and sometimes not. In my local it works. I contact the web server admin and I ask what is the status of the session on the server and How does it execute it's web requests? (Sockets, file_get_contents, curl?). They said that No problems reproduced with Server Sessions and PHP Curl works fine. I know it's weird but can somebody here can figure it out what is the problem behind of it.