I have developed a SharePoint add-ins where I am retrieving information from a SQL server through an API that is hosted on Azure developed in asp.net web API. I am using "/_api/SP.WebProxy.invoke" method to get information from Web API. It has been working since last 3 years but now I am getting error as "An exception occurred while trying to establish a connection with the remote server - 'The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel"
I checked Web API and it is working fine everywhere else, but not in SharePoint Hosted Add-In. We even checked SSL certificate and it is valid, not expired, and returns the correct response when accessed via Postman.
Please help.
