Interesting fix. I had to do all six steps. It worked on all servers.

As a side note, I did not have this issue on one of our servers. The primary difference between the server that worked and the servers I applied the steps to is internet access - the exception occurred on the servers that cannot make outbound requests.

Additionally, I found that if I just deleted the first line of that file, it worked.

Hope this info helps!

EDIT:

I did confirm that in my case, the web server is attempting an outbound HTTP request to W3C for the DTD.