Cause of "Unable to verify the first certificate" error in an HTTP Request Step in Procedures

The reason why you may be receiving this error is that the HTTP URL does not have a valid SSL certificate. If there is a certificate, it may be self-signed, which is not allowed in the HTTP Request step due to it being untrustworthy. To remedy this, whomever maintains the URL needs to retrieve a valid SSL certificate from a trustworthy source.