I try to download the logs from my Google App Engines with the command: 

```
appcfg.py request_logs [directory]  mylogs.txt

```

However, I encountered the server error as below:

```
C:\Program Files (x86)\Google\google_appengine>appcfg.py request_logs E:\PhD\cod
e\python\webDevelop\similarAPI\similarAPI/  mylogs.txt
05:22 PM Application: similarapi
05:22 PM Host: appengine.google.com
05:22 PM Downloading request logs for app similarapi version 1.
Error 500: --- begin server output ---

Server Error (500)

A server error has occurred.
--- end server output ---

```

I have looked at the [official document](https://cloud.google.com/appengine/docs/standard/python/tools/downloading-logs) and related [Stack Overflow questions](https://stackoverflow.com/questions/2229293/download-log-from-appengine-including-python-log-statements), but no clues are found. Actually I can get the logs in Dec, 2016 but not now. And I tried it for one week without the success, so it should not be the error of Google's infrastructure. 

Does anyone know how to solve that problem? Thanks in advance.