Xdebug: [Step Debug] Could not connect to debugging client. Tried: localhost:9003 (fallback through xdebug.client_host/xdebug.client_port) :-(

Question

What is the workaround of this message for xdebug ang php?

Xdebug: [Step Debug] Could not connect to debugging client. Tried: localhost:9003 (fallback through xdebug.client_host/xdebug.client_port) :-(

This message showup when I run composer update on WSL2 installed with UBUNTU 20.01.

My current php version is php8 and xdebug3

Update:

This is the x-debug section

xdebug

__   __   _      _
\ \ / /  | |    | |
 \ V / __| | ___| |__  _   _  __ _
  > < / _` |/ _ \ '_ \| | | |/ _` |
 / . \ (_| |  __/ |_) | |_| | (_| |
/_/ \_\__,_|\___|_.__/ \__,_|\__, |
                              __/ |
                             |___/

Version => 3.0.1
Support Xdebug on Patreon, GitHub, or as a business: https://xdebug.org/support

Feature => Enabled/Disabled
Development Aids => ✘ disabled
Coverage => ✘ disabled
GC Stats => ✘ disabled
Profiler => ✘ disabled
Step Debugger => ✔ enabled
Tracing => ✘ disabled

Debugger => enabled
IDE Key =>

Directive => Local Value => Master Value
xdebug.auto_trace => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.auto_trace" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.auto_trace"
xdebug.cli_color => 0 => 0
xdebug.client_discovery_header => no value => no value
xdebug.client_host => localhost => localhost
xdebug.client_port => 9003 => 9003
xdebug.cloud_id => no value => no value
xdebug.collect_assignments => Off => Off
xdebug.collect_includes => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.collect_includes" => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.collect_includes"
xdebug.collect_params => 0 => 0
xdebug.collect_return => Off => Off
xdebug.collect_vars => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.collect_vars" => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.collect_vars"
xdebug.connect_timeout_ms => 200 => 200
xdebug.coverage_enable => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.coverage_enable" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.coverage_enable"
xdebug.default_enable => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.default_enable" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.default_enable"
xdebug.discover_client_host => On => On
xdebug.dump.COOKIE => no value => no value
xdebug.dump.ENV => no value => no value
xdebug.dump.FILES => no value => no value
xdebug.dump.GET => no value => no value
xdebug.dump.POST => no value => no value
xdebug.dump.REQUEST => no value => no value
xdebug.dump.SERVER => no value => no value
xdebug.dump.SESSION => no value => no value
xdebug.dump_globals => On => On
xdebug.dump_once => On => On
xdebug.dump_undefined => Off => Off
xdebug.file_link_format => no value => no value
xdebug.filename_format => no value => no value
xdebug.force_display_errors => Off => Off
xdebug.force_error_reporting => 0 => 0
xdebug.gc_stats_enable => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.gc_stats_enable" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.gc_stats_enable"
xdebug.gc_stats_output_dir => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.gc_stats_output_dir" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.gc_stats_output_dir"
xdebug.gc_stats_output_name => gcstats.%p => gcstats.%p
xdebug.halt_level => 0 => 0
xdebug.idekey => no value => no value
xdebug.log => no value => no value
xdebug.log_level => 7 => 7
xdebug.max_nesting_level => 256 => 256
xdebug.max_stack_frames => -1 => -1
xdebug.mode => debug => debug
xdebug.output_dir => /mnt/c/www/traces => /mnt/c/www/traces
xdebug.overload_var_dump => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.overload_var_dump" => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.overload_var_dump"
xdebug.profiler_append => Off => Off
xdebug.profiler_enable => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_enable" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_enable"
xdebug.profiler_enable_trigger => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_enable_trigger" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_enable_trigger"
xdebug.profiler_enable_trigger_value => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_enable_trigger_value" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_enable_trigger_value"
xdebug.profiler_output_dir => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_output_dir" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.profiler_output_dir"
xdebug.profiler_output_name => cachegrind.out.%p => cachegrind.out.%p
xdebug.remote_autostart => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_autostart" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_autostart"
xdebug.remote_connect_back => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_connect_back" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_connect_back"
xdebug.remote_enable => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_enable" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_enable"
xdebug.remote_host => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_host" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_host"
xdebug.remote_log => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_log" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_log"
xdebug.remote_log_level => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_log_level" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_log_level"
xdebug.remote_mode => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_mode" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_mode"
xdebug.remote_port => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_port" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_port"
xdebug.remote_timeout => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_timeout" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.remote_timeout"
xdebug.scream => Off => Off
xdebug.show_error_trace => Off => Off
xdebug.show_exception_trace => Off => Off
xdebug.show_local_vars => Off => Off
xdebug.show_mem_delta => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.show_mem_delta" => This setting has been removed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#removed-"xdebug.show_mem_delta"
xdebug.start_upon_error => default => default
xdebug.start_with_request => 1 => 1
xdebug.trace_enable_trigger => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.trace_enable_trigger" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.trace_enable_trigger"
xdebug.trace_enable_trigger_value => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.trace_enable_trigger_value" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.trace_enable_trigger_value"
xdebug.trace_format => 0 => 0
xdebug.trace_options => 0 => 0
xdebug.trace_output_dir => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.trace_output_dir" => This setting has been changed, see the upgrading guide at https://xdebug.org/docs/upgrade_guide#changed-"xdebug.trace_output_dir"
xdebug.trace_output_name => trace.%c => trace.%c
xdebug.trigger_value => no value => no value
xdebug.var_display_max_children => 128 => 128
xdebug.var_display_max_data => 512 => 512
xdebug.var_display_max_depth => 3 => 3

Answer 1

What causes that message in the first place:

You have xdebug.start_with_request = yes (which is the same as xdebug.remote_autostart = yes for Xdebug v2). This option tells Xdebug to try to debug every single request/script regardless of the "debug me" flag.

If Xdebug fails to connect to the debug client (values from xdebug.client_host & xdebug.client_port .. or autodetected host if xdebug.discover_client_host is enabled) then it notifies you about that.

How to prevent it from appearing on my screen/in the output:

Xdebug uses standard PHP routines to write such warnings (e.g. standard PHP error_log() function). Normally such a message will be written to the standard PHP's error log. Looks like you do not have it configured at all in your php.ini (empty value) therefore PHP sends it to your standard output instead (so you still can have a chance to see it, as it might be important).

The solution is to point PHP's error_log ini setting to some valid location so you can read it when needed (path depends on your OS & distro, e.g. error_log = /var/log/php_error.log would be very common). If you do not need such log at all (have other logging system in place) -- use /dev/null or something similar instead.

---

You can also try xdebug.log_level = 0 but this should prevent Xdebug from logging anything, even if you specify xdebug.log.

---

Please also see this explanation from Xdebug author on "why it works this way": https://stackoverflow.com/a/65670743/783119

Answer 2

From the documentation of Xdebug about this kind of errors:

Occurs when Xdebug is trying to connect to a debuging client to start a debugging session.

The debugger could not make a connection to the client. The error message indicates which host and port combinations were tried, and through which configuration options it came to that conclusion.

An example:

Could not connect to debugging client. Tried: ::1:9003 (from REMOTE_ADDR HTTP header), localhost:9003 (fallback through xdebug.client_host/xdebug.client_port)

This message indicates that Xdebug first tried to use ::1:9003 (IPv6's localhost) from the REMOTE_ADDR header, and then it fell back to localhost:9003 as configured with xdebug.client_host and xdebug.client_port.

Suggested solutions:

• Check whether your debugging client is listening on the indicated address and port. On Linux and OSX, you can use netstat -a -n | grep LISTEN to check.
• Change xdebug.client_host and/or xdebug.client_port to the right address/hostname and port of where the debugging client is listening.

Answer 3

I'm using: xdebug.start_with_request=trigger to trigger xdebug when I need it(with use of browser xdebug extension for web server debugging).

Or if I need to debug php script(using cli), I use phpstorm with configuration like this:

With this approach, I don't get this error and can use xdebug logs as always.

Answer 4

I use Xampp and this is what I have in php.ini

[xdebug]
zend_extension=xdebug
xdebug.mode=develop,debug

When I want to debug some code, I use this FireFox add-on

Then I click on this button and activate debug mode:

This way I do not need to add xdebug.start_with_request = yes to the php.ini file and I will use xdebug just when I need it.

---

Update:

I just realized that if you enable this add-on but you forget to set a break point in your code you will see the error again which makes sense.

Answer 5

Disable the xdebug browser extension when you aren't using it.

I use the VSCode debugger. When debugging was off in the IDE I was seeing the error in the log on every page visit because my chrome browser extension was still trying to invoke xdebug.

This happens despite having good php.ini settings for xdebug like:

xdebug.mode=debug

or

xdebug.start_with_request=trigger

Both documented here: Xdebug: Documentation