Professional Communication
Software Development Tools

OPC Foundation member and certified logos

Online Forums

Technical support is provided through Support Forums below. Anybody can view them; you need to Register/Login to our site (see links in upper right corner) in order to Post questions or issues. You do not have to own a commercial license in order to use the OPC Labs support. Our team is actively monitoring the forums, and provides replies as soon as possible.

Please read Rules for forum posts before reporting your issue or asking a question. OPC Labs team is actively monitoring the forums, and replies as soon as possible.

Various technical information can also be found in our Knowledge Base. For your convenience, we have also assembled a Frequently Asked Questions page.

Do not use the Contact page for technical issues.

OPCUA: Frequent connection drops

More
15 Oct 2026 08:57 #14730 by Andriy
Replied by Andriy on topic OPCUA: Frequent connection drops
Hello,
I will let you know once the customer installs the patch and we confirm whether it resolves the issueBest regards

Please Log in or Create an account to join the conversation.

More
11 Oct 2026 09:50 #14727 by support
Replied by support on topic OPCUA: Frequent connection drops
Update:

There is now one more build, QuickOPC 5.84.416, with an additional unrelated fix (memory leak in specific scenario), so if you can, just use this latest one.

Best regards
 
The following user(s) said Thank You: Andriy

Please Log in or Create an account to join the conversation.

More
10 Oct 2026 13:26 #14726 by support
Replied by support on topic OPCUA: Frequent connection drops
Hello.

We have found "something" that might be causing the problem (unfortunately it cannot be verified with 100% certainty, because it is timing-dependent, and we do not have a local repro). Essentially, we believe that the session keep-alive algorithm in the UA-.NETStandard makes wrong calculations.

We have now implemented a work-around and multiple other measures to prevent this problem.

Please rebuild and retest with QuickOPC 5.84.415 (packages are now on nuget.org. and the installer on our Web site).

Thank your for reporting the issue and your cooperation in diagnosing it.

Best regarads
 

Please Log in or Create an account to join the conversation.

More
08 Oct 2026 10:01 #14725 by support
Replied by support on topic OPCUA: Frequent connection drops
Hello.

I have received the new capture & application log.
It now has the information I asked for.

And, it appears that there is no "wrong-doing" on the OPC UA server part (or the network). So we will look into what can be causing the error on our side.

I will report here when I have more information.

Best regards
 

Please Log in or Create an account to join the conversation.

More
08 Oct 2026 08:10 #14723 by Andriy
Replied by Andriy on topic OPCUA: Frequent connection drops
Hello,
Thank you for the prompt response. I sent you another Wireshark trace file by email
Best regards

Please Log in or Create an account to join the conversation.

More
07 Oct 2026 14:27 #14722 by support
Replied by support on topic OPCUA: Frequent connection drops
Hello.
I received the application log file, thank you.

The last "keep-alive" error in the application log file is at 15:15:21.
The Wireshark capture is from 15:19:46 to 15:31:55.

So there is no keep-alive error that I can correlate.

Regards
 

Please Log in or Create an account to join the conversation.

More
07 Oct 2026 13:16 #14721 by support
Replied by support on topic OPCUA: Frequent connection drops
Also,

please confirm what were the QuickOPC settings when the Wireshark capture was taken. Was it as you wrote, i.e.

sessionParameters.HoldPeriod = 60 * 1000;        // 60 seconds (default: 5 seconds)
sessionParameters.KeepAliveInterval = 60 * 1000; // 60 seconds (default: 5 seconds)
sessionParameters.SessionTimeout = 5 * 60 * 1000; // 5 minutes (default: 1 minute)

or were they at the defaults at that time?

Thank you

Please Log in or Create an account to join the conversation.

More
07 Oct 2026 12:54 #14720 by support
Replied by support on topic OPCUA: Frequent connection drops
Hello.

I received the Wireshark trace, thank you. But here is what I wrote originally:

"We will need a WireShark log of the communication, and the corresponding log from the QuickOPC application, with timestamps attempting to correlate the two."

There are multiple OPC UA sessions sequence in the Wireshark trace. I do not know which at which points QuickOPC reported the keep-alive problem, and at which points it did not. 

The logs from your app with QuickOPC errors are from September 29. The Wireshark trace is from September 23.

Regards
 

Please Log in or Create an account to join the conversation.

More
07 Oct 2026 10:35 #14719 by support
Replied by support on topic OPCUA: Frequent connection drops
Hello.

Please use support09 (at) opclabs.com.

Regards
 

Please Log in or Create an account to join the conversation.

More
07 Oct 2026 09:56 #14718 by Andriy
Replied by Andriy on topic OPCUA: Frequent connection drops
Hello,
I have received approval to send you Wireshark trace. Please confirm the email address to which I should send it

Please Log in or Create an account to join the conversation.

Moderators: support, vaclav.zaloudek
Time to create page: 0.136 seconds