Why does the OPC UA server reject the specified user identity token when using the OPC `connect` function in MATLAB?

I have succesfully created an OPC UA client object in MATLAB using the opcua() function in Industrial Communication Toolbox. However, I get the following error when trying to connect this client to the server using the connect() function via the username/password, or user certificate user indentity token.

The user identity token is valid but the server has rejected it.

Answer 1

[MathWorks Industrial Communication Toolbox Team]

This error typically occurs when the server's security policy or configuration settings do not match the user identity token being used. It could be due to factors such as an incorrect username or password, expired or revoked user credentials, insufficient privileges, or incompatible security settings between the client and server.

To resolve this issue, you may need to verify the correctness of the user credentials, ensure that the user has the necessary permissions to access the requested resources, and confirm that the security settings on the server side align with the client's expectations. Additionally, reviewing the server's logs or consulting the OPC UA server documentation may provide further insights into the specific reason for rejecting the user identity token.

For example, in the Prosys Simulation Server, click the "Users" tab and ensure the following:

• The required authentication methods/ User Identity Token types such as anonymous, Username & Password, and certificates are enabled.
• If you are connecting via the Username&Password token type, make sure the user is added to the "Users" list.
• If you are connecting via an X509 user certificate token type, the server log may provide further insights into the specific reason for rejecting the user identity token.