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=b080e8a574&notice_str=0181785530&hash=7126899845f1e69feba57c99b74e26b5&redirect_to=https%3A%2F%2Fu.limo%2Fpr%2F' caused an error:

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