Running the debugger results in "There was an error in starting the debug server"

Environment data

VS Code version: Version 1.19.3 (1.19.3) Python Extension version: 2018.1.0 Python Version: 2.7.13 OS and version: macOS High Sierra 10.13.2 (17C205)

Actual behavior

When attempting to debug a Python file, as soon as it is launched I get an error in the debug console as well as an alert banner with the message: There was an error in starting the debug server. Error = {"code":"ENOTFOUND","errno":"ENOTFOUND","syscall":"getaddrinfo","address":"localhost"}

The debugger does not start. I used the debugger successfully previously. That was a few months ago at this point, so I have no idea what versions are different or what has changed on the host machine.

Expected behavior

The file should be debugged as normal.

Steps to reproduce:

• Open a .py script
• Select the debugger tab on the left
• Select the “Python” configuration (launch.json is below)
• Click the run button

Logs

Output from Python output panel

There was an error in starting the debug server. Error = {"code":"ENOTFOUND","errno":"ENOTFOUND","syscall":"getaddrinfo","address":"localhost"}
There was an error in starting the debug server. Error = {"code":"ENOTFOUND","errno":"ENOTFOUND","syscall":"getaddrinfo","address":"localhost"}

Output from Console window (Help->Developer Tools menu)

/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:249 [Extension Host] Python Extension: Failed to get conda info from conda null
t.log @ /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:249
/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:2742 There was an error in starting the debug server. Error = {"code":"ENOTFOUND","errno":"ENOTFOUND","syscall":"getaddrinfo","hostname":"localhost"}
e.doShow @ /Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:2742

Contents of launch.json:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python",
            "type": "python",
            "request": "launch",
            "stopOnEntry": true,
            "pythonPath": "${config:python.pythonPath}",
            "program": "${file}",
            "cwd": "${workspaceFolder}",
            "env": {},
            "envFile": "${workspaceFolder}/.env",
            "debugOptions": [
                "RedirectOutput"
            ]
        }
   ]
}

python.pythonPath is set to use the Homebrew Python at /usr/local/bin/python2

[DoctorDYL]

Finally, I found my macOS system hosts file is empty and I fixed this problem with adding “127.0.0.1 localhost” to hosts file.

[dalemyers]

@breadplop The hosts file tells your machine about special hostnames. More info here: https://en.wikipedia.org/wiki/Hosts_(file)