Windows version 2019 IIS-10
Coldfusion 2016 with update-11
this.serialization.preservecaseforstructkey = true;
This creates CGI struct with keys in uppercase letters. According to Microsoft that CGI keys are in uppercase. As CF is not case sensitive but somehow this caused problems when accessing CGI with lowercase cgi.server_name (returns empty when preservecaseforstructkey setting is enabled)
Fix: access CGI key with uppercase letters e.g CGI.HTTP_HOST
CGI keys with uppercase letters will be consistent with the rest of code base. some places cgi key are in uppercase.