I have a .NET 4.6, MVC 5 web application making a REST call to another service using OAUTH.
The web application is deployed on Azure's App Service.
Most of the time, it works perfectly.
Both my App and the Target API use SSL and I have tested both on SSLabs.com, and both come out at A and supporting TLS1.2
However occasionally the the API link seems to get "knocked out" and all calls produce the error:
The request was aborted: Could not create SSL/TLS secure channel.
This is logged in our Elmah log.
The only way to resolve this at present is to restart the Azure App Service.
I have researched this ie
The request was aborted: Could not create SSL/TLS secure channel for HttpWebRequest
Only one App Service (live) seems affected. This may be because it is used more and trigger the problem sooner. The QA one seems fine. QA is used fairly heavily due to testing activities. Not sure if this is circumstantial
I have now hit a dead end. Key clue may be in having to restart the App Service to get it working again.
Any pointers appreciated.
Many thanks.