How to trouble shoot SSL PR_END_OF_FILE_ERROR?

Hello

I have installed phoenix server and installed certificate using lets-encrypt and installed the certificate with phoenix server, but when I try to access the website using https, I got this error in browser:

Secure Connection Failed

An error occurred during a connection to ngspice.dcaclab.com. PR_END_OF_FILE_ERROR

    The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
    Please contact the website owners to inform them of this problem.

I am using arch linux, Where to start trouble shooting?
Thanks