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=44368a18eb&notice_str=1043852962&hash=0ef9bd34335c6c0d9ba521d62f80db8c&redirect_to=https%3A%2F%2Fu.limo%2F14657%2F' caused an error:

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