The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel in SharePoint 2013 Server environment
Issue Could not establish trust relationship for the SSL/TLS secure channel with authority Environment: SharePoint 2013 Farm with multiple nodes connected to connected to load balancer have a Service Oriented architecture to connect other services from SharePoint app servers SharePoint Nodes are connected to other services using services oriented services using endpoint defined Symptoms : SharePoint servers are communicate with Remote service using https protocol using SSL. When I check the validity of the remote certificate from the browser It depicts it is valid. Resolution I took while me to figure this out. It is true it is about the certificate but it is not the end certificate. certificate chain is broken in the Intermediate level. You can find this easily by checking details from Certificate. Then navigate to Certification Path You should see these Root and Intermediate as verified. If they are not valid or expired, you will see a warning sign near to the certificate