Hello,
at this moment (about two days ago) I have updated only engine (external, not self hosted) from 4.2.7.5 to 4.2.8.2

As soon as I'm starting for the first time a VM with an ovn based nic I get what below in ovirt-provider-ovn.log

In admin gui, if I try for example to start via "run once" I get:
"
Error while executing action Run VM once: Failed to communicate with the external provider, see log for additional details.
"
Any clue?
Thanks,
Gianluca

2019-01-29 17:23:20,554 root Starting server
2019-01-29 17:23:20,554 root Version: 1.2.18-1
2019-01-29 17:23:20,555 root Build date: 20190114151850
2019-01-29 17:23:20,555 root Githash: dae4c1d
2019-01-29 18:04:15,575 root Starting server
2019-01-29 18:04:15,576 root Version: 1.2.18-1
2019-01-29 18:04:15,576 root Build date: 20190114151850
2019-01-29 18:04:15,576 root Githash: dae4c1d
2019-02-01 14:26:58,316 root From: ::ffff:127.0.0.1:49582 Request: GET /v2.0/ports
2019-02-01 14:26:58,317 root HTTPSConnectionPool(host='engine-host', port=443): Max retries exceeded with url: /ovirt-engine/sso/oauth/token-info (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fe806166b90>: Failed to establish a new connection: [Errno -2] Name or service not known',))
Traceback (most recent call last):
  File "/usr/share/ovirt-provider-ovn/handlers/base_handler.py", line 134, in _handle_request
    method, path_parts, content
  File "/usr/share/ovirt-provider-ovn/handlers/selecting_handler.py", line 175, in handle_request
    return self.call_response_handler(handler, content, parameters)
  File "/usr/share/ovirt-provider-ovn/handlers/neutron.py", line 33, in call_response_handler
    TOKEN_HTTP_HEADER_FIELD_NAME, '')):
  File "/usr/share/ovirt-provider-ovn/auth/plugin_facade.py", line 31, in validate_token
    return auth.core.plugin.validate_token(token)
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/authorization_by_username.py", line 36, in validate_token
    return self._is_user_name(token, _admin_user_name())
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/authorization_by_username.py", line 47, in _is_user_name
    timeout=AuthorizationByUserName._timeout())
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 131, in get_token_info
    timeout=timeout
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 54, in wrapper
    response = func(*args, **kwargs)
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 47, in wrapper
    raise BadGateway(e)
BadGateway: HTTPSConnectionPool(host='engine-host', port=443): Max retries exceeded with url: /ovirt-engine/sso/oauth/token-info (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fe806166b90>: Failed to establish a new connection: [Errno -2] Name or service not known',))
2019-02-01 14:27:26,968 root From: ::ffff:127.0.0.1:49590 Request: GET /v2.0/ports
2019-02-01 14:27:26,969 root HTTPSConnectionPool(host='engine-host', port=443): Max retries exceeded with url: /ovirt-engine/sso/oauth/token-info (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fe80618df50>: Failed to establish a new connection: [Errno -2] Name or service not known',))
Traceback (most recent call last):
  File "/usr/share/ovirt-provider-ovn/handlers/base_handler.py", line 134, in _handle_request
    method, path_parts, content
  File "/usr/share/ovirt-provider-ovn/handlers/selecting_handler.py", line 175, in handle_request
    return self.call_response_handler(handler, content, parameters)
  File "/usr/share/ovirt-provider-ovn/handlers/neutron.py", line 33, in call_response_handler
    TOKEN_HTTP_HEADER_FIELD_NAME, '')):
  File "/usr/share/ovirt-provider-ovn/auth/plugin_facade.py", line 31, in validate_token
    return auth.core.plugin.validate_token(token)
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/authorization_by_username.py", line 36, in validate_token
    return self._is_user_name(token, _admin_user_name())
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/authorization_by_username.py", line 47, in _is_user_name
    timeout=AuthorizationByUserName._timeout())
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 131, in get_token_info
    timeout=timeout
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 54, in wrapper
    response = func(*args, **kwargs)
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 47, in wrapper
    raise BadGateway(e)
BadGateway: HTTPSConnectionPool(host='engine-host', port=443): Max retries exceeded with url: /ovirt-engine/sso/oauth/token-info (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fe80618df50>: Failed to establish a new connection: [Errno -2] Name or service not known',))
2019-02-01 14:29:17,412 root From: ::ffff:127.0.0.1:49616 Request: GET /v2.0/ports
2019-02-01 14:29:17,412 root HTTPSConnectionPool(host='engine-host', port=443): Max retries exceeded with url: /ovirt-engine/sso/oauth/token-info (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fe80618de50>: Failed to establish a new connection: [Errno -2] Name or service not known',))
Traceback (most recent call last):
  File "/usr/share/ovirt-provider-ovn/handlers/base_handler.py", line 134, in _handle_request
    method, path_parts, content
  File "/usr/share/ovirt-provider-ovn/handlers/selecting_handler.py", line 175, in handle_request
    return self.call_response_handler(handler, content, parameters)
  File "/usr/share/ovirt-provider-ovn/handlers/neutron.py", line 33, in call_response_handler
    TOKEN_HTTP_HEADER_FIELD_NAME, '')):
  File "/usr/share/ovirt-provider-ovn/auth/plugin_facade.py", line 31, in validate_token
    return auth.core.plugin.validate_token(token)
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/authorization_by_username.py", line 36, in validate_token
    return self._is_user_name(token, _admin_user_name())
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/authorization_by_username.py", line 47, in _is_user_name
    timeout=AuthorizationByUserName._timeout())
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 131, in get_token_info
    timeout=timeout
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 54, in wrapper
    response = func(*args, **kwargs)
  File "/usr/share/ovirt-provider-ovn/auth/plugins/ovirt/sso.py", line 47, in wrapper
    raise BadGateway(e)
BadGateway: HTTPSConnectionPool(host='engine-host', port=443): Max retries exceeded with url: /ovirt-engine/sso/oauth/token-info (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7fe80618de50>: Failed to establish a new connection: [Errno -2] Name or service not known',))