Xdebug: [Step Debug] Time-out Connecting to Debugging Client, Waited: 200 Ms. Tried: Localhost:9003

I also encountered with such an error after updting my Xdebug library to 3+ version.

What I found out is that new setting xdebug.start_with_request = yes configures Xdebug to establish a connection on every request.

Meanwhile the official doc offers to use xdebug.start_with_request = trigger in order to connect Xdebug only if the need for it was explicitly indicated. In this case I can start step debugging process with passing an extra key via GET parameters, for example , but this is inconvenient for me, all I want is press F5 within my VSCode to start debugging as I always did.

So my solution is the following. I left start_with_request = yes and turned off most of Xdebug notifications by passing xdebug.log_level = 0. Then i override log_level within launch.json file to enable all warnings but only within debugging session.

php.ini:

[XDebug]
zend_extension = php_xdebug-3.0.4-7.4-vc15-x86_64.dll
xdebug.mode = debug,develop
xdebug.discover_client_host = yes
xdebug.log_level = 0
xdebug.log = "%sprogdir%/userdata/temp/xdebug/log.txt"
xdebug.start_with_request = yes
xdebug.idekey = VSCODE

launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Listen for XDebug",
            "type": "php",
            "request": "launch",
            "port": 9003,
            "env": {
                "XDEBUG_CONFIG": "log_level=7",
            }
        }
    ]
}

I encountered the same issue with PHP8. In my case, it was just the XDebug version suggested by their own wizard. I use this version and it works just fine. 3.0.0-8.0-vs16

launch.json:

       {
            "name": "Listen for Xdebug",  
            "type": "php",  
            "request": "launch",  
            "port": 9003,  
            "hostname": "localhost",  
            "pathMappings": {
                "/var/www/html": "${workspaceRoot}/www/"
            },
        },

change pathmappings according to your requirements and the most important is hostname. after i added that, it worked

I got this error message after my computer started to use a different IP address. The reason why the change happened was that after I disconnected it from the ethernet cable, it connected to the wifi router, which meant a new IP address.

The solution was to change the /etc/php/8.1/apache2/php.ini file. I modified the line xdebug.client_host=192.168.1.110 to xdebug.client_host=192.168.1.107 where the new value comes from the output of the ipconfig command.