I've had the same issue too. I made Adobe aware of it, but they weren't particularly forthcoming or helpful in getting it sorted.
I gave up.
You def have RDS enabled, yeah? The bits 'n' pieces you need to uncomment in web.xml are uncommented? This was not the cause of my problem, but it has been the cause of other people's problems in the same area.
thanks for the reply. Since yesterday I found out that it may have something to do with my Firewall/Proxy. I'm using Microsoft TMG. The reasoning behind this is when I VPN in and then connect to RDS, the connection is fine, however if I try connecting from outside the network it talks to the server but I get the "com" error message. The thing is that everything works fine for previous versions of CF just not this one, very strange.
Any ideas or suggestions is very helpful, I need this working ASAP. BTW are there any specific ports that CF X uses for RDS other than port 80?
Ok I found out what my issue was and resolved it. For some reason in my situation, in order to connect to the RDS the host's FQDN must be the same domain as my network.
So if my domain is abc.com
then webserver.123.com won't work (even though the 123.com is pointing to the correct IP and routed correctly to the server).
It must be webserver.abc.com (even though the settings are exactly the same as webserver.123.com).
Anyway, didn't have this issue before with CF 8 or 9. Weird, just thought I'd let everyone know what my result is.