Windows 10 – Chrome ERR_SSL_PROTOCOL_ERROR on known working site

When I connect to https://www.feeguarantee.com, Chrome gives me an ERR_SSL_PROTOCOL_ERROR.  Firefox gives SSL_ERROR_RX_RECORD_TOO_LONG.  Edge gives some generic error.  

All other sites appear to work fine, including sites I know to be hosted on the same server machine.  Others using my network are able to connect to the site fine as well.

The DNS is hosted in Cloudflare and uses Cloudflare’s flexible SSL mode.  However, when I disable Cloudflare, I get the same issue using the certificate installed directly on our server.  Other sites using Cloudflare’s SSL work fine.

Curl reports as follows

$ curl -v https://www.feeguarantee.com* Rebuilt URL to: https://www.feeguarantee.com/*   Trying 162.242.219.59...* Connected to www.feeguarantee.com (162.242.219.59) port 443 (#0)* successfully set certificate verify locations:*   CAfile: C:Program Files (x86)Gitbincurl-ca-bundle.crt  CApath: none* TLSv1.0, TLS handshake, Client hello (1):* error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol* Closing connection 0curl: (35) error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

Chrome suggested to run the windows diagnostic tool, so I did and it reported the winsock protocol wasn’t installed.  I followed instructions here http://www.kapilarya.com/windows-sockets-registry-entries-required-for-network-connectivity-is-missing to reset my winsock drivers, ran into the group policy issue, and installed the registry files they provided.  Retrying step two still failed, but the diagnostic tool no longer reports the problem.

I have also tried reinstalling/updating my network and chipset drivers to no avail.

Short of a clean install of Windows, how can I fix this issue?

Solution:

This is often a result of old DNS cache information in Chrome… To clear it enter:

chrome://net-internals/#dns

In the address bar, and click “Clear host cache”, then attempt to load the Web page again. It may be a good idea to flush your windows dns cache as well with the command line entry of

ipconfig /flushdns