Questions:
- 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?
Solution:
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 https://api.nexmo.com/tlsverification 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.
