Sending an ACME HTTP validation request to www.debian.pl results in an unacceptable redirect. This is most likely a misconfiguration of your web server or your web application.
Too many (10) redirects, last redirect was to: http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
Trace:
@0ms: Making a request to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test (using initial IP 2a02:c40:1:2::1)
@0ms: Dialing 2a02:c40:1:2::1
@207ms: Server response: HTTP 301 Moved Permanently
@207ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@310ms: Server response: HTTP 301 Moved Permanently
@310ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@413ms: Server response: HTTP 301 Moved Permanently
@413ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@516ms: Server response: HTTP 301 Moved Permanently
@516ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@619ms: Server response: HTTP 301 Moved Permanently
@619ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@722ms: Server response: HTTP 301 Moved Permanently
@722ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@825ms: Server response: HTTP 301 Moved Permanently
@825ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@928ms: Server response: HTTP 301 Moved Permanently
@928ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@1031ms: Server response: HTTP 301 Moved Permanently
@1031ms: Received redirect to http://www.debian.pl/.well-known/acme-challenge/letsdebug-test
@1134ms: Server response: HTTP 301 Moved Permanently
A test authorization for www.debian.pl to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
Fetching http://www.debian.pl/.well-known/acme-challenge/rS8Z-lNhF3DIUOrlzSd9FJAdQOMyUPbyHCs167bzwFY: Too many redirects
www.debian.pl has multiple IP addresses in its DNS records. While they appear to be accessible on the network, we have detected that they produce differing results when sent an ACME HTTP validation request. This may indicate that some of the IP addresses may unintentionally point to different servers, which would cause validation to fail.
[Address=2a02:c40:1:2::1,Address Type=IPv6,Server=Apache/2.4.38 (Debian),HTTP Status=301,Number of Redirects=10,Final HTTP Status=301] vs [Address=195.66.73.43,Address Type=IPv4,Server=Apache/2.4.38 (Debian),HTTP Status=404]