Finally got a chance to do some testing.
This likely means that Komodo isn't connected to the proxy. Confirm Debug menu > Listen for debugging session is selected. From your step by step notes above, you really gloss over step 2 which is a really important step and is what the error above is pointing to, a mis-configured Komodo.
By following the docs I did the following:
1. started the proxy:
pydbgpproxy -i 10.19.0.148:10000 -d localhost:10001
2. Configured Komodo (IP is obfuscated but it's the IP of the server I'm running the proxy on):
3. Double checked that Komodo was listening to a proxy under `Debug menu > Listener Status:
4. Ran my script:
python pydbgp -d localhost:10001 -k "careyh" test-proxy.py
Successful connection output from proxy, starting with my IDE connecting at line
4 and then the sample app connecting at line 5 and a debugging session starting in Komodo:
INFO: dbgp.proxy: starting proxy listeners. appid: 27371
INFO: dbgp.proxy: dbgp listener on localhost:10001
INFO: dbgp.proxy: IDE listener on 10.19.0.148:10000
INFO: dbgp.proxy: Server:onConnect ('10.19.10.91', 55618) [proxyinit -p 10000 -k careyh -m 1]
INFO: dbgp.proxy: connection from 127.0.0.1:58908 [<__main__.sessionProxy instance at 0x27dc8c0>]
So have a look at your Komodo configuration.