Address a 'Proxy failed to connect to Middleware Server' error

If communication with the MES middleware is down and the Logger shows the message Proxy failed to connect to Middleware Server service endpoint, perform the following steps to verify that the middleware configuration is correct.

1. From the command prompt on the client application node, use the ping command to verify that there is TCP/IP connectivity with the Middleware Server node.

2. On the Middleware Server node:

   • In the post-install Configurator, verify that the MES DB/MW Communication component is installed correctly and its status is Configured (green indicator).

   • From the Windows Services app or from the Service panel, verify that the Wonderware MES Middleware Host service is running.

   • Verify that a firewall inbound rule exception has been added to Windows Defender Firewall Allowed Apps page with the name MES Middleware TCP NetBinding and that its Domain and Private check boxes are selected. Or verify that the Windows Domain Networks firewall status is off.

   • Verify whether Certificate Revocation Checking is enabled in the Middleware Configuration Editor. If it is, and the current certificate does not have a Certificate Revocation List (CRL) or is self-signed, do the following:

     1. If the certificate is self-signed, disable certificate revocation checking.

     2. If the certificate does not have certificate revocation list, acquire a certificate with a CRL and use the updated certificate.

     3. If the certificate's certificate revocation list points to a domain, ensure the domain of the local node matches the domain listed in the CRL.

     4. Reconfigure the MES Middleware Proxy component. For more information, see Configure the MES middleware proxy.

3. If the MES middleware and client middleware proxy are on different nodes, then in the post-install Configurator on each node verify that the HTTP and HTTPS port numbers configured for the MES Middleware Proxy component on the client proxy node match those configured for the MES Middleware Proxy component on the Middleware Server node.

   If the MES middleware and client middleware proxy are on the same node, then in the post-install Configurator verify that the HTTPS port number configured for the MES Middleware Proxy component is the same HTTPS port number configured for the System Management Server (click Advanced and refer to the Ports tab on the Advanced Configuration dialog).

4. If the MES middleware and client middleware proxy are on different nodes, then in the post-install Configurator verify the following about the System Management Server:

   • If the System Management Server configuration on the Middleware Server node is set to This node is the System Management Server, then the System Management Server configuration on the client middleware proxy node should be set to Connect to an existing System Management Server and point to the Middleware Server node.

   • If the System Management Server configuration on the Middleware Server node is set to Connect to an existing System Management Server and the configured target node is different than the client middleware proxy node, then the System Management Server configuration on the client middleware proxy node should use the option Connect to an existing System Management Server and use the same target node name of the System Management Server that is configured on the Middleware Server node. That is, the target node being pointed to as the location of the existing System Management Server should be the same on the Middleware Server and client middleware proxy nodes.

   • If the System Management Server configuration on the Middleware Server node is set to Connect to an existing System Management Server and the configured target node is same as the client middleware proxy node, then the System Management Server configuration on the client middleware proxy node should be set to This node is the System Management Server.

5. In the post-install Configurator on the node where the System Management Server resides, verify that the System Management Server status is Configured (green indicator).