As suggested in the error message, use the DEBUG option like so:
filename foo url
'http://support.sas.com/techsup/service_intro.html'
debug
;
This will return the communication between SAS and the web server, this will help you identify the problem. For the URL it looks like this:
NOTE: >>> GET /techsup/service_intro.html HTTP/1.0
NOTE: >>> Host: support.sas.com
NOTE: >>> Accept: */*
NOTE: >>> Accept-Language: en
NOTE: >>> Accept-Charset: iso-8859-1,*,utf-8
NOTE: >>> User-Agent: SAS/URL
NOTE: >>>
NOTE: <<< HTTP/1.1 301 Moved Permanently
NOTE: <<< Date: Tue, 13 Jun 2017 07:36:15 GMT
NOTE: <<< Server: Apache
NOTE: <<< Location: https://support.sas.com/techsup/service_intro.html
NOTE: <<< Content-Length: 258
NOTE: <<< Connection: close
NOTE: <<< Content-Type: text/html; charset=iso-8859-1
NOTE: <<< Set-Cookie: BIGipServer~WEB~www.sas.com-pool=1074113941.20480.0000; path=/; Httponly
NOTE: <<<
NOTE: >>> GET /techsup/service_intro.html HTTP/1.0
NOTE: >>> Host: support.sas.com
NOTE: >>> Accept: */*
NOTE: >>> Accept-Language: en
2 The SAS System 09:36 Tuesday, June 13, 2017
NOTE: >>> Accept-Charset: iso-8859-1,*,utf-8
NOTE: >>> Cookie: BIGipServer~WEB~www.sas.com-pool=1074113941.20480.0000
NOTE: >>> User-Agent: SAS/URL
NOTE: >>>
NOTE: <<< HTTP/1.1 404 Not Found
NOTE: <<< Date: Tue, 13 Jun 2017 07:36:16 GMT
NOTE: <<< Server: Apache
NOTE: <<< Expires: Thu, 01 Jan 1970 00:00:00 GMT
NOTE: <<< X-Powered-By: Jetty(9.2.9.v20150224)
NOTE: <<< Content-Type: text/html; charset=UTF-8
NOTE: <<< Set-Cookie: renderid=rend03; path=/;
NOTE: <<< Set-Cookie: JSESSIONID=lqmlrqwb58pdwzzq8yvyei0w;Path=/
NOTE: <<< Connection: close
NOTE: <<<
ERROR: Invalid reply received from the HTTP server. Use the debug option for more info.
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