[BitBucket user: Alain Mazy]
[BitBucket date: 2018-01-18.09:49:24]

got the problem again while using the dicom-web plugin.  Here's a full excerpt of the logs:
Forwarding study to dicom-web server xxx
```
E0118 09:37:35.886484 PluginsManager.cpp:197] Exception while invoking plugin service 27: Error in the network protocol
E0118 09:37:35.886522 PluginsManager.cpp:164] Cannot issue an HTTP query to https://xxx.xxx/dicom-web/studies (HTTP status: 0)
E0118 09:37:35.887153 PluginsErrorDictionary.cpp:111] Exception inside the plugin engine: Error in the network protocol
Failed to forward study: Orthanc HTTP API exception: '500 - Unknown Orthanc HTTP Rest API exception' while accessing 'http://localhost:8042/dicom-web/servers/xxx/stow'
```