"An existing connection was forcibly closed by the remote host"


  • Why does my application throw an exception "An existing connection was forcibly closed by the remote host."?
  • I can send API requests using curl or Postman, but when I use my existing integration the application fails. Why is that?  
  • My application was working before, and now it suddenly fails? 


It is possible that your application is using a deprecated TLS version when sending HTTPs requests to Nexmo. Please note that Legacy TLS version 1 and 1.1 were permanently disabled for all public endpoints on 21st August 2018 at 9:20 UTC, due to serious security vulnerabilities in these protocols. 

We recommend that you are using correct TLS version by making an HTTP request to the following URL from your application. This end-point will return a 200 OK if the application correctly supports TLS v 1.2 and a 400 error if not.


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