We are running an OPC UA Server using Unified Automation .NET Server SDK version 2.5.8 (.NET Framework 4.7.1) and ran into an error occurring in various circumstances.
The error is:
We usually have about 70-90 unique clients. One of the clients was a Siemens OPC UA Client for WinCC that was causing problems but they are no longer connected.MAXCHANNELCOUNT: Connection rejected because the maximum number of channels.
Since they disconnected, we have not had the MAXCHANNELCOUNT error and everything was running fine.
Today, we were upgrading a separate system on our IT infrastructure that caused the OPC UA Server to be disconnected from the backend that feeds it data. This is something we have done many times without problems.
During the upgrade, all OPC UA Clients were disconnected and we could not connect with UaExpert due to a BadCommunicationError.
The application log for the OPC UA Server has not unusual errors but the SDK log file was filled with MAXCHANNELCOUNT errors.
We tried to restart the OPC UA Server Windows Service but it could not be stopped. We had to restart the entire OS in order to get the OPC UA Server back up and running. Once it restarted, there were no more issues or errors.
Besides the MAXCHANNELCOUNT errors, hundreds of the following errors were found in the SDK log file:
Could something in the IT infrastructure or another application on the same OS be causing this error?TCPSERVERCHANNEL ForceChannelFault Socket=00000DAC, ChannelId=38, TokenId=65, Reason=[BadTcpInternalError]BeginReceive failed. BeginReceive failed. An established connection was aborted by the software in your host machine
TCPSERVERCHANNEL SOCKET ATTACHED: 00002664, ChannelId=38357
Channel 38344 cleaned up automatically.
Channel 39724 no longer exists.
Should the MaxChannelCount be increased in the application configuration file as below? Could this cause problems?
Code: Select all
<Extension>
<TransportSettings xmlns="http://unifiedautomation.com/schemas/2011/12/Application.xsd">
<MaxChannelCount>500</MaxChannelCount>
</TransportSettings>
</Extension>
Sincerely,
Jonathan