Certify validation of the required challenges did not complete successfully


I have installed a Blazor WebAssembly Application on IIS.
Now, I am trying to get a Lets-Encrypt-certificate for the application.
I have configured it. When I press “Test”, all is working. When I press “Request Certificate”, I will get an error.
You will find the log attached. I hope, you can help me.
Thank you very much.


Hi, the issue is that your firewall is blocking port 80 (http) either at the windows firewall level or at the VM/cloud level.

The local test works because your firewall isn’t blocking locally.