Error: 404 Not Found

Sorry, the requested URL 'http://u.limo/wp-admin/admin-ajax.php?channel_id=social_wechat&action=xh_social_channel&tab=login_redirect_to_authorization_uri&xh_social_channel=eae32193e9&notice_str=4550942811&hash=7e1b7b0b9e1ed09fd157b4a43e65e2b7&redirect_to=https%3A%2F%2Fu.limo%2F12419%2F' caused an error:

Not found: '/wp-admin/admin-ajax.php'