System.Net.HttpWebException when using IIS SEO Toolkit

Question

When running IIS SEO toolkit on my customer's site I am getting the following error:

The link to 'https://www.my-client-website.censored/' has resulted in an error.
Details: System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel.
   at System.Net.HttpWebRequest.GetResponse()
   at Microsoft.Web.Management.SEO.Crawler.UrlDownloader.OnGetContent(CrawlerProcessContext context)

The site is being served by nginx and rails, and I do not find any errors in the logs. Currently, I do not know how can I troubleshot this issue or what might be its cause. Does anyone has suggestions about how should I further troubleshoot this issue?

Answer 1

There were two issues with my website:

One was that I was redirecting https://domain to https://www.domain The other was that the IIS SEO Toolkit does not support TLSv1.2 and my nginx was configured to only support TLSv1.2. I thus had to temporarily comment the redirect rule and add TLSv1 support with corresponding ciphers in order to crawl the website.