Nginx Proxy manager API error

Installation
1

I have installed Nginx Proxy Manager.
When I want to add a SSL Certficate I get error when testing "Communication with the API failed, is NPM running correctly? .
Before i used Nginx ssl proxy and ducdns (to create certificate) without a problem.
Port on router are open for 80 like before.

Try removing duckdns, restart .

2

I had the same problem.
Just create the ssl Certificate. Connect it to your host.
Then disable and enable the host. SSL should be installed and working.

This worked with me.

Good luck