App Engine Go部署失败求助：部署成功后回滚报500错误

Yesterday afternoon, my Go App Engine application deployed without any issues. But today, every deployment attempt fails. I'm using the command goapp deploy MY_DIR/app.yaml to deploy, and here's the full deployment log:

02:38 PM Host: appengine.google.com 
02:38 PM Application: MY_APP; module: MY_MOD; version: MY_VER 
02:38 PM Starting update of app: exp-lkl, module: MY_MOD, version: MY_VER 
02:38 PM Getting current resource limits. 
02:38 PM Scanning files on local disk. 
02:38 PM Scanned 500 files. 
02:38 PM Scanned 1000 files. 
02:38 PM Cloning 1085 application files. 
02:38 PM Compilation starting. 
02:38 PM Compilation: 1081 files left. 
02:38 PM Compilation completed. 
02:38 PM Starting deployment. 
02:38 PM Checking if deployment succeeded. 
02:38 PM Will check again in 1 seconds. 
02:38 PM Checking if deployment succeeded. 
02:38 PM Will check again in 2 seconds. 
02:38 PM Checking if deployment succeeded. 
02:38 PM Will check again in 4 seconds. 
02:38 PM Checking if deployment succeeded. 
02:38 PM Will check again in 8 seconds. 
02:38 PM Checking if deployment succeeded. 
02:38 PM Will check again in 16 seconds. 
02:38 PM Checking if deployment succeeded. 
02:39 PM Deployment successful. 
02:39 PM Checking if updated app version is serving. 
02:39 PM Rolling back the update. Error 500: 
--- begin server output --- 
<h3>Server Error</h3><p>A server error has occurred.</p> 
--- end server output ---

I've already tried the following troubleshooting steps, but none of them resolved the issue:

• Updated the SDK to the latest version
• Switched between Go versions (tested go1.6 and go1.8)
• Deployed using the appcfg.py tool instead of goapp

All attempts result in the same Error 500 and auto-rollback. Could anyone help me figure out what's going wrong here?

内容的提问来源于stack exchange，提问作者Xin