在我登录后安装phabricator后出现空白页面

I have succefully installed phabricator on ubuntu but when I registered the admin user blank page appears. Even I tried to recover the user using ./bin/auth recover user but it did not work. It just shows the login page and then white blank page. Even I have to clear the browser cache to see the login page again. Please help.I have succefully installed phabricator on ubun