+++ This bug was initially created as a clone of Bug #1438962 +++ In Bug 1438962 we added more logging to the UI about connection status, but the connection is still failing on Nate's system. I believe this is due to `await DebuggerClient.socketConnect` never resolving, but we don't see any relevant errors in the UI or stdout.

Pushed up a try run with extra logging for testing: https://treeherder.mozilla.org/#/jobs?repo=try&revision=b0a40f18e1035f77bbdc830f794c845a72768e5e. Locally (testing with `~/Desktop/Nightly.app/Contents/MacOS/firefox --profile /tmp/debugger-1 --jsdebugger`) I see: ``` console.log: "DebuggerSocket.connect 1" console.log: "DebuggerSocket.connect 2" console.log: "DebuggerSocket.connect 3" ({host:"localhost", port:"65113", webSocket:false, authenticator:{}}) console.log: "DebuggerSocket.connect 4" "localhost" "65113" (void 0) ({}) (void 0) console.log: "_getTransport 1" console.log: "_getTransport 3" console.log: "Debugging connection starting authentication on 127.0.0.1:65122" console.log: "_handle 1" console.log: "_handle 2" console.log: "_handle 3" console.log: "_handle 4" console.log: "_handle 5" console.log: "Debugging connection allowed on 127.0.0.1:65122" console.log: "Server cert accepted? true" console.log: "_getTransport 4" console.log: "DebuggerSocket.connect 5" ({_input:({}), _scriptableInput:({}), _output:({}), _incomingHeader:"", _incoming:null, _outgoing:[], hooks:null, active:false, _incomingEnabled:true, _outgoingEnabled:true, close:function bound close() { [native code] }}) console.log: "DebuggerSocket.connect 6" console.log: "DebuggerSocket.connect 7" ``` On the system where it's failing, we see: ``` console.log: "DebuggerSocket.connect 1" console.log: "DebuggerSocket.connect 2" console.log: "DebuggerSocket.connect 3" ({host:"localhost", port:"64207", webSocket:false, authenticator:{}}) console.log: "DebuggerSocket.connect 4" "localhost" "64207" (void 0) ({}) (void 0) console.log: "_getTransport 1" console.log: "_getTransport 3" 2018-07-19 12:56:04.957 plugin-container[47886:10770309] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0xab37, name = 'com.apple.tsm.portname' See /usr/include/servers/bootstrap_defs.h for the error codes. 2018-07-19 12:56:05.103 plugin-container[47886:10770309] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0xab53, name = 'com.apple.coredrag' See /usr/include/servers/bootstrap_defs.h for the error codes. 2018-07-19 12:56:05.796 plugin-container[47887:10770371] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0x8a3f, name = 'com.apple.tsm.portname' See /usr/include/servers/bootstrap_defs.h for the error codes. 2018-07-19 12:56:05.938 plugin-container[47887:10770371] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0x8abb, name = 'com.apple.coredrag' See /usr/include/servers/bootstrap_defs.h for the error codes. ```

The _handle calls that are missing in the bad run are triggered as a result of nsIServerSocketListener.onSocketAccepted: https://searchfox.org/mozilla-central/rev/8384a6519437f5eefbe522196f9ddf5c8b1d3fb4/devtools/shared/security/socket.js#545-550. Probably need more logging, but we aren't making it to _attemptTransport. I'm thinking I'll need to add more logging to _attemptConnect (https://searchfox.org/mozilla-central/rev/8384a6519437f5eefbe522196f9ddf5c8b1d3fb4/devtools/shared/security/socket.js#249), which is probably what's failing.

Any unusual security settings or firewalls? Maybe try checking for open ports doing something odd (on macOS, try `lsof -i -n -P -sTCP:LISTEN`).