Hello.

The expected upon server restart, when monitored item subscriptions are present, is roughly as follows:

1. When the server shuts down, all subscribed monitored items receive an error through DataChangeNotification (.Exception is not null). The precise errors depends on many factors.
2. ServerConditionChanged event is raised, optionally with Disconnecting, but then certainly with Disconnected status.
3. QuickOPC should make reconnection attempts (observable through ServerConditionChanged going to Connecting etc.). Monitored items may receive additional errors to update their status. When a connection attempt succeeds, ServerConditionChanged with Connected should be raised, and all monitored items should eventually receive valid data.

I disagree with that the error message is misleading. it uses the words "the server may have rejected", clearly indicating that what the message is describes is just one of possible causes of the error. It would use the words "the server has rejected" if it was the only option.

I agree that QuickOPC should reconnect. I tried but I could not reproduce the issue. There are many ways the server can go about disconnecting/restarting, so something is different in your tests. I therefore have additional questions:

1. Which OPC Server are you using?
2. How do you restart it?
3. Is the server on your PC or on the network?
4. You reported that you get ServerConditionChanged event with Disconnecting. Do you also get one with Disconnected? (my understanding is that you do not Disconnected, but want to be 100% sure).

Regards

 

.NET Core 8, QuickOPC v.5.84.294 and v5.84.192.Scenario:
1. UA client is initialized with property Isolated = true, EasyUAClientCore.SharedParameters.EngineParameters.ReconnectPeriod is explicitly set to 2000 
2. Client is connected and active subscription exists for several OPC UA items
3. Quickly restart the OPC UA server4. "OnDataChangeNotification" event (sometimes) is fired for all subscribed items with error like:

"OpcLabs.EasyOpc.UA.Engine.UAEngineException: OPC-UA client session is not available when connecting the client subscription. Session error: "OPC UA service result - {BadSecureChannelClosed}. [80860000]."

and additional misleading message like

"The server may have rejected the connection because it does not trust the client (e.g. certificate problem); check the diagnostics on the server side, if possible."

4. "OnServerConditionChanged" event is fired with EasyUAServerConditionChangedEventArgs.ConnectionState = "Disconnecting" and error like 

"Error: OpcLabs.UAEngine=4704 The OPC-UA server has shut down or is in the process of shutting down. The application is releasing all connections to this server. The application will try to reconnect to the server after a configurable period.
+ The client method called (or event/callback invoked) was 'ServerConditionChanged'.
OpcLabs.EasyOpc.UA.Engine.UAEngineException: The OPC-UA server has shut down or is in the process of shutting down. The application is releasing all connections to this server. The application will try to reconnect to the server after a configurable period.
+ The client method called (or event/callback invoked) was 'ServerConditionChanged'."

5. No more reconnect attempts happened. "ServerConditionChanged" event or "OnDataChangeNotification" are never invoked again regardless of server state. No TCP communication with the server. If not reproduced, go to (step 3).

The issue is not reproducible with QuickOPC v.5.83.1181, where ServerConditionChanged is subsequently fired with 'Disconnected', then 'Connecting', then 'Connected'