Why I can't debug PHP with Xdebug in Sublime Text?

Question

My operating system is Ubuntu 18.04

My stack is XAMPP (LAMPP).

I have installed Xdebug as indicated by the official page . I also have the extension to debug in Chrome.

When I try to debug PHP code ( Tools > Xdebug > start debugging and then F5 in Chrome where my file is on my local server) it doesn't interrupt at breakpoint. I can see Xdebug windows but nothing happens.

If I go to Tools > Xdebug > Restart session I get a window that says:

Unable to start xdebug session, another application is already listening on configured port (9000)

I don't know if it has to do with the real error.

I have investigated that I have to configure an Xdebug.sublime-settings file, there is one default and another user, in the user I have nothing, and the default looks like this:

{
// For remote debugging to resolve the file locations
// it is required to configure the path mapping
// with the server path as key and local path as value.
//
// Make sure to use absolute path when defining server path,
// because Xdebug debugger engine does not return symbolic links.
//
// Example:
// "/absolute/path/to/file/on/server" : "/path/to/file/on/computer",
// "/var/www/htdocs/example/" : "C:/git/websites/example/"
"path_mapping": {

},

// Determine which URL to launch in the default web browser
// when starting/stopping a session.
"url": "",

// An IDE key is used to identify with debugger engine
// when Sublime Text will start or stop a debugging session.
//
// This package does not filter sessions by IDE key,
// it will accept any IDE key, also ones that do not match this configured IDE key.
// It is merely used when launching the default web browser with the configured URL.
"ide_key": "sublime.xdebug",

// Host address of network interface which Sublime Text
// should listen to connect with debugger engine.
//
// By specifying "" or "0.0.0.0" as host address, Sublime Text
// will listen on all the configured network interfaces.
// This is the desired configuration when debugging
// a script that is located on a remote server.
//
// Otherwise it is recommended to use "127.0.0.1" or "localhost"
// as configuration, when debugging a script on your local machine.
// Due to the fact that by listening on all the configured
// network interfaces raises a security concern as anyone
// can access Sublime Text through the configured port.
//
// When specifying host address of network interface,
// be sure to specify an IPv4 address as Sublime Text
// will listen for connections through an IPv4 socket.
"host": "",

// Which port number Sublime Text should listen
// to connect with debugger engine.
"port": 9000,

// Maximum amount of array children
// and object's properties to return.
"max_children": 32,

// Maximum amount of
// variable data to initially retrieve.
"max_data": 1024,

// Maximum amount of nested levels to retrieve
// of array elements and object properties.
"max_depth": 1,

// Break at first line on session start, when debugger engine has connected.
"break_on_start": false,

// Break on exceptions, suspend execution
// when the exception name matches an entry in this list value.
"break_on_exception": [
    // E_ERROR, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR
    "Fatal error",
    // E_RECOVERABLE_ERROR (since PHP 5.2.0)
    "Catchable fatal error",
    // E_WARNING, E_CORE_WARNING, E_COMPILE_WARNING, E_USER_WARNING
    "Warning",
    // E_PARSE
    "Parse error",
    // E_NOTICE, E_USER_NOTICE
    "Notice",
    // E_STRICT
    "Strict standards",
    // E_DEPRECATED, E_USER_DEPRECATED (since PHP 5.3.0)
    "Deprecated",
    // 0
    "Xdebug",
    // default
    "Unknown error"
],

// Always close debug windows and restore layout on session stop.
"close_on_stop": false,

// Show information about super globals in context view.
"super_globals": true,

// Display property by fullname in context view.
"fullname_property": true,

// Do not show possible password values in context view.
"hide_password": false,

// Render evaluated result as parsed output instead of raw XML.
"pretty_output": false,

// Always launch browser on session start/stop.
// Note: This will only work if you have the 'url' setting configured.
"launch_browser": false,

// When launching browser on session stop do not execute script.
// By using parameter XDEBUG_SESSION_STOP_NO_EXEC instead of XDEBUG_SESSION_STOP.
"browser_no_execute": false,

// Do not use the debugging window layout.
"disable_layout": false,

// Window layout that is being used when debugging.
"debug_layout" : {
    "cols": [0.0, 0.5, 1.0],
    "rows": [0.0, 0.7, 1.0],
    "cells": [[0, 0, 2, 1], [0, 1, 1, 2], [1, 1, 2, 2]]
},

// Group and index positions for debug views.
"breakpoint_group": 2,
"breakpoint_index": 1,
"context_group": 1,
"context_index": 0,
"stack_group": 2,
"stack_index": 0,
"watch_group": 1,
"watch_index": 1,

// Custom gutter icons for indicating current line or enabled/disabled breakpoints.
//
// Do not use same icon for following values, because Sublime Text is unable
// to use the same icon for different scopes, in case there are duplicate icons
// detected it will fall back to the corresponding icon in the package.
"breakpoint_enabled": "circle",
"breakpoint_disabled": "dot",
"breakpoint_current": "",
"current_line": "bookmark",

// Path to Python installation on your system.
// Which is being used to load missing modules.
//
// It is recommended to configure your Python path for Sublime Text 2
// especially on older UNIX systems, where some modules (xml.parsers.expat)
// might be missing and could improve performance of package.
//
// Example:
// "python_path" : "/usr/lib/python2.7"
"python_path" : "",

// Show detailed log information about communication
// between debugger engine and Sublime Text.
// Log can be found at Packages/User/Xdebug.log
"debug": false

I am a noob in backend, I have no idea how to configure that file, also, I am new in Linux, I had never had to configure a debugger (since I simply used Visual Studio).

Any other technical detail that I need to give, I update it immediately.

Answer 1

Check your "php.ini" and confirm that xdebug is set to port 9000...
In some environments port 9000 may already be in use by some other application.. try updating php and sublime to use another port (such as 9001)