咨询如何解决Ubuntu16.04上运行Nvidia Digits6.1.1的导入报错问题

在安装了Ubuntu 16.04的个人电脑上部署Nvidia Digits 6.1.1版本，全程严格按照官方指引完成所有安装步骤，启动Digits服务时弹出如下错误堆栈：

Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/home/kenan/digits/digits/__main__.py", line 70, in <module>
    main()
  File "/home/kenan/digits/digits/__main__.py", line 55, in main
    import digits.webapp
  File "digits/webapp.py", line 7, in <module>
    from flask_socketio import SocketIO
  File "/usr/local/lib/python2.7/dist-packages/flask_socketio/__init__.py", line 16, in <module>
    import socketio
  File "/home/kenan/.local/lib/python2.7/site-packages/socketio/__init__.py", line 3, in <module>
    from .client import Client
  File "/home/kenan/.local/lib/python2.7/site-packages/socketio/client.py", line 7, in <module>
    import engineio
  File "/home/kenan/.local/lib/python2.7/site-packages/engineio/__init__.py", line 3, in <module>
    from .client import Client
  File "/home/kenan/.local/lib/python2.7/site-packages/engineio/client.py", line 2, in <module>
    from json import JSONDecodeError
ImportError: cannot import name JSONDecodeError

当前为部署完成启动服务失败，需要相关排查思路与解决方案建议。

核心问题定位 #

JSONDecodeError 是Python 3.5及以上版本新增的内置异常类，Python 2.7内置的json模块中未定义该异常。当前环境通过pip安装的socketio、engineio组件为适配Python 3.x的高版本，和Digits 6.1.1所依赖的Python 2.7运行环境不兼容，最终触发导入失败错误。

可落地解决步骤 #

• 卸载当前环境中安装的不兼容高版本依赖包，执行命令：
  pip2 uninstall -y python-socketio python-engineio flask-socketio
• 安装与Digits 6.1.1适配的指定版本依赖：
  • pip2 install python-socketio==4.6.1
  • pip2 install python-engineio==3.14.2
  • pip2 install flask-socketio==3.3.2
• 安装完成后重新执行Digits启动命令，验证服务可正常加载web管理界面。

内容的提问来源于stack exchange，提问作者Kenan Baysal