This could be due to one of the following:
- Misconfiguration: The URI specified in the ApplicationDescription does not match the application/product URI configured in the Certificate. This could be due to a typo, additional space, or an incorrect configuration during the setup of the application instance certificate. Double-check the ApplicationDescription and ensure that the URI specified in it matches the application/product URI in the Certificate. Correct any configuration errors if found.
- Certificate mismatch: The URI in the Certificate does not match the URI expected by the client. This can happen if the Certificate used by the OPC UA server is outdated, or if the server's URI has changed but the Certificate has not been updated accordingly. If the server's URI has changed, generate a new Certificate with the updated URI and replace the old Certificate with the new one.
- Network proxy or firewall: If the OPC UA communication is passing through a network proxy or firewall, it is possible that the URI in the Certificate is modified or rewritten, causing a mismatch with the URI specified in the ApplicationDescription. If there is a network proxy or firewall in place, review its configuration to ensure it is not modifying the URI in the Certificate. Adjust the settings if necessary to allow the correct URI to pass through.
