Hi,

We are using Java version 4.2.0-955 build.

There had been a network issue on our customer’s network where they had 7 different OpcUa servers and all the connections were stable and healthy. We create unique UaClient for each connection. After the network loss 6 of the clients were successfully able to reconnect to their respective OpcUa servers via auto reconnect, but 1 of the UaClient couldnt recover.

When we check the logs of UaClient for the problematic one, it was as below;

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2024-09-20 17:16:12,776 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.TcpConnection | sendRequest: token=SecurityToken(Id=2, secureChannelId=-757636602, creationTime=Sep 20, 2024 5:16:12 PM, lifetime=3600000)
2024-09-20 17:16:12,776 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.TcpConnection | sendRequest: keySize=0
2024-09-20 17:16:12,776 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.ChunkFactory | ChunkFactory: class=class com.prosysopc.ua.stack.transport.tcp.impl.ChunkFactory
2024-09-20 17:16:12,777 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.ChunkFactory | allocate: chunkSize=57
2024-09-20 17:16:12,777 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.SecureChannelTcp | serviceRequest: Message sent, requestId=288 secureChannelId=-757636602
2024-09-20 17:16:12,777 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.SecureChannelTcp | serviceRequest: message=CloseSecureChannelRequest [RequestHeader=”null”]
2024-09-20 17:16:12,777 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.SecureChannelTcp | -757636602 Closed
2024-09-20 17:16:12,779 TcpConnection/Read | c.p.u.s.t.t.i.TcpConnection | /10.251.190.23:4840 Closed (expected)
2024-09-20 17:16:12,779 PublishTask-com.prosysopc.ua.client.UaClient@6e789e87 | c.p.u.s.t.t.i.TcpConnection | /10.251.190.23:4840 Closed
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It all ended over here and we dont receive any messages, exceptions from this UaClient anymore. It is as if it got stuck on some lock or something like that on SecureChannelTcp.

To give a successful example from one of the other 6, please check below logs;

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2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.TcpConnection | pruneInvalidTokens: tokens(2)=[SecurityToken(Id=1, secureChannelId=-209045690, creationTime=Sep 20, 2024 4:30:52 PM, lifetime=3600000), SecurityToken(Id=2, secureChannelId=-209045690, creationTime=Sep 20, 2024 5:15:52 PM, lifetime=3600000)]
2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.TcpConnection | tokens=[SecurityToken(Id=1, secureChannelId=-209045690, creationTime=Sep 20, 2024 4:30:52 PM, lifetime=3600000), SecurityToken(Id=2, secureChannelId=-209045690, creationTime=Sep 20, 2024 5:15:52 PM, lifetime=3600000)]
2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.TcpConnection | getSecurityTokenToUse=SecurityToken(Id=2, secureChannelId=-209045690, creationTime=Sep 20, 2024 5:15:52 PM, lifetime=3600000)
2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.TcpConnection | sendRequest: token=SecurityToken(Id=2, secureChannelId=-209045690, creationTime=Sep 20, 2024 5:15:52 PM, lifetime=3600000)
2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.TcpConnection | sendRequest: keySize=0
2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.ChunkFactory | ChunkFactory: class=class com.prosysopc.ua.stack.transport.tcp.impl.ChunkFactory
2024-09-20 17:16:12,865 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.ChunkFactory | allocate: chunkSize=57
2024-09-20 17:16:12,866 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.SecureChannelTcp | serviceRequest: Message sent, requestId=295 secureChannelId=-209045690
2024-09-20 17:16:12,866 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.SecureChannelTcp | serviceRequest: message=CloseSecureChannelRequest [RequestHeader=”null”]
2024-09-20 17:16:12,866 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.SecureChannelTcp | -209045690 Closed
2024-09-20 17:16:12,866 TcpConnection/Read | c.p.u.s.t.t.i.TcpConnection | /10.251.190.21:4840 Closed (expected)
2024-09-20 17:16:12,867 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.TcpConnection | /10.251.190.21:4840 Closed
2024-09-20 17:16:12,867 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.SecureChannelTcp | requests.clear()
2024-09-20 17:16:12,870 PublishTask-com.prosysopc.ua.client.UaClient@1ccaf4b4 | c.p.u.s.t.t.i.SecureChannelTcp | initialize: url=opc.tcp://10.251.190.21:4840
————

and it goes and succeeds afterwards to recover.

As we have seen, for the problematic one we never get to the requests.clear() step and something between that and the previous log has to be causing the issue on the other one.

Can you please help us solve this issue as its quite crucial for us to address that. If the proposal is going to be updating the Java client version to 5.x.x, can you also please provide more information on what that suggestion depends on.

Thanks.