在K2HostServer.config中更改netfxversion

在K2 Blackpearl的安装目录里找到K2HostServer.config文件，修改如下：

<appSettings>
    <!-- 
        Time in seconds. Default is 1 Hour. This setting determines the amount of time before the server will check if any groups in the cache needs to be refreshed. 
        This setting must either be shorter, or the same amount of time as the GroupCacheInterval setting. 
      -->
    <add key="GroupCachePollingInterval" value="3600" />
    <!-- 
        Time in seconds. Default is 1 Hour. This setting determines the amount of time the group will be cached before it is refreshed. 
        This setting must either be longer or the same amount of time as the GroupCachePollingInterval setting. 
      -->
    <add key="GroupCacheInterval" value="3600" />
    <add key="netfxversion" value="v4.0.30319" />
  </appSettings>