Let's Encrypt certificates generation error

I spoke too soon. It was still giving error.

I came across another discussion here and that helped solve the issue for me.
I am posting it here so that it might help someone else.

https://community.blynk.cc/t/raspberry-pi-3-server-ssl-certificates/9318

I modified the server.properties (As per @Costas)

client.ssl.cert=server.crt
client.ssl.key=server.pem

Now everything is working well.