我正在尝试通过letencrypt在GCE上获得SSL，但是卡住了。
cert-manager窗格记录以下内容：
cert-manager/controller/certificates "msg"="re-queuing item due to error processing" "error"="applying acme order back-off for certificate production/khw-tls-cm because it has failed within the last 1h0m0s" "key"="production/khw-tls-cm"
怎么了？