HTTPort is a useful tool for http tunneling of http, but the documentation is incomplete.  Here are a few errors and solutions I’ve encountered.

httport errors:

• SOCKS4[x.x.x.x:80]: 0002 Access denied
• Means that "httport/Proxy/Use personal remote host at/Password" != "htthost/options/personal password"
• SOCKS4[x.x.x.x:80]: 0103 Invalid connection id
• "Proxy/HTTP Proxy to bypass/Host name or IP address" doesn't point to the proxy to bypass
• HTTPx: WinInet HTTPSendRequest failed (12029) (request xyz, attempt n/m)
• "Proxy/HTTP Proxy to bypass/Host name or IP address" doesn't point to the proxy to bypass
• SOCKS4[x.x.x.x:80]: 0103 Invalid connection id
• Means that "httport/Proxy/Use personal remote host at/Host name or IP address" != the external IP address of your htthost server
  

htthost errors:

• LISTENER: bind() to 0.0.0.0:8080 failed, closing socket
• Means that some other process is listening on port 8080.  One cause of this could be that you're running htthostc (console mode) and htthost.  This happened to me after I set up to run htthostc as a service, but forgot to take htthost out of the Startup folder.