By Osama Salama

2015-03-13 15:09:32 8 Comments

I configured everything for PhpStorm and xdebug to work, I'm running Ubuntu 14.04.

the connection back to the IDE is not established, and I get this in the IDE event Log

Cannot accept external Xdebug connection: Cannot evaluate expression 'isset($_SERVER['PHP_IDE_CONFIG'])' – Osama Salama 13 mins ago

I'll put together configuration values I configured in various places. As I can't find out where is the problem


zend_extension = /usr/lib/php5/20121212/
xdebug.remote_connect_back = 1
xdebug.remote_autostart = 1

PHP info


xdebug support  enabled
Version 2.3.1

Supported protocols Revision
DBGp - Common DeBuGger Protocol $Revision: 1.145 $

Directive   Local Value Master Value

xdebug.auto_trace   Off Off
xdebug.cli_color    0   0
xdebug.collect_assignments  Off Off
xdebug.collect_includes On  On
xdebug.collect_params   0   0
xdebug.collect_return   Off Off
xdebug.collect_vars Off Off
xdebug.coverage_enable  On  On
xdebug.default_enable   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.extended_info    On  On
xdebug.file_link_format no value    no value
xdebug.force_display_errors Off Off
xdebug.force_error_reporting    0   0
xdebug.halt_level   0   0
xdebug.idekey   no value    no value
xdebug.max_nesting_level    256 256
xdebug.max_stack_frames -1  -1
xdebug.overload_var_dump    On  On
xdebug.profiler_aggregate   Off Off
xdebug.profiler_append  Off Off
xdebug.profiler_enable  Off Off
xdebug.profiler_enable_trigger  Off Off
xdebug.profiler_enable_trigger_value    no value    no value
xdebug.profiler_output_dir  /tmp    /tmp
xdebug.profiler_output_name cachegrind.out.%p   cachegrind.out.%p
xdebug.remote_autostart On  On
xdebug.remote_connect_back  On  On
xdebug.remote_cookie_expire_time    3600    3600
xdebug.remote_enable    On  On
xdebug.remote_handler   dbgp    dbgp
xdebug.remote_log   /home/nautilus/Desktop/xdebug.log   /home/nautilus/Desktop/xdebug.log
xdebug.remote_mode  req req
xdebug.remote_port  9000    9000
xdebug.scream   Off Off
xdebug.show_exception_trace Off Off
xdebug.show_local_vars  Off Off
xdebug.show_mem_delta   Off Off
xdebug.trace_enable_trigger Off Off
xdebug.trace_enable_trigger_value   no value    no value
xdebug.trace_format 0   0
xdebug.trace_options    0   0
xdebug.trace_output_dir /tmp    /tmp
xdebug.trace_output_name    trace.%c    trace.%c
xdebug.var_display_max_children 128 128
xdebug.var_display_max_data 512 512
xdebug.var_display_max_depth    3   3

I also validated the remote debugging env. it's all good. which also came out fine.

The last possible resort is the xdebug log file:

Log opened at 2015-03-13 14:39:01
I: Checking remote connect back address.
W: Remote address not found, connecting to configured address/port: :-|
I: Connected to client. :-)
-> <init xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" fileuri="dbgp://stdin" language="PHP" protocol_version="1.0" appid="4474"><engine version="2.3.1"><![CDATA[Xdebug]]></engine><author><![CDATA[Derick Rethans]]></author><url><![CDATA[]]></url><copyright><![CDATA[Copyright (c) 2002-2015 by Derick Rethans]]></copyright></init>
<- feature_set -i 1 -n show_hidden -v 1
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" command="feature_set" transaction_id="1" feature="show_hidden" success="1"></response>
<- feature_set -i 2 -n max_depth -v 1
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" command="feature_set" transaction_id="2" feature="max_depth" success="1"></response>
<- feature_set -i 3 -n max_children -v 100
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" command="feature_set" transaction_id="3" feature="max_children" success="1"></response>
<- status -i 4
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" command="status" transaction_id="4" status="starting" reason="ok"></response>
<- step_into -i 5
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" command="step_into" transaction_id="5" status="stopping" reason="ok"></response>
<- eval -i 6 -- aXNzZXQoJF9TRVJWRVJbJ1BIUF9JREVfQ09ORklHJ10p
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="" command="eval" transaction_id="6"><error code="5"><message><![CDATA[command is not available]]></message></error></response>
Log closed at 2015-03-13 14:39:01


@Augustas 2018-06-06 14:08:53

Also same error if you missed to set environment variable in docker-compose.yml for your workspace configuration:

workspace: build: environment: - PHP_IDE_CONFIG=${PHP_IDE_CONFIG}

@George Appleton 2018-11-05 11:08:04

Where is the bash variable supposed to come from?

@Mage2.PRO 2017-05-15 06:14:29

Debugging a file named «test.php» in IntelliJ IDEA / PhpStorm can lead to the «Cannot evaluate expression 'isset($_SERVER['PHP_IDE_CONFIG'])'» failure.
Use another name for file.

@Gregory R. Sudderth 2017-07-06 08:17:00

This is exactly what happened to me!

@popstr 2017-02-23 07:54:48

I had this problem as well and tried every trick I could find, but nothing worked. For me, debugging works most of the time, but sometimes it just stops working with the message: "Cannot accept external Xdebug connection: Cannot evaluate expression 'isset($_SERVER['PHP_IDE_CONFIG'])'"

So I eventually realized I had a compilation error in my code (misspelled method name - PhpStorm does not always report these things, at least in my setup). As soon as I corrected the error debugging started working again. Maybe this can help someone struggling.

Although I still have issues with breakpoints not being hit, I can throw in a "xdebug_break();" line in the code and debugging becomes more reliable. The downside with using xdebug_break instead of breakpoints is (apart from the fact that it's more work than just adding a breakpoint) the local variables not being displayed in the PhpStorm debugger for some reason (only globals are shown). That makes debugging less convenient, but at least I can make it work.

Apparently you can't have everything :) Coming from the Java world, good debugging is just something I have been able to take for granted, but I have now realized how spoiled I have been :)

@Edwin Ikechukwu 2017-11-30 01:50:03

i can relate...i was spoilt from the c# world too ¯_(ツ)_/¯

@Buttle Butkus 2016-02-01 07:46:52

I had the exact same error in PhpStorm as the OP.

This answer to a different question solved the problem for me, but I would like to add more detail in my own answer.

The main issue was improperly loaded xdebug. The server mapping issues mentioned in other answers was not an issue for me.

If you load your phpinfo() page and find the xdebug section, and you see this:



Then you have to fix that before you try anything else! But sometimes this can take some work to track down, if you have multiple php.ini files.

Also in your phpinfo() page, search for "php.ini", (it should be right near the top) and see your "Configuration File (php.ini) Path", and your "Loaded Configuration File". Those are where your xdebug may be loading.

enter image description here

In my case, I correctly loaded it as a Zend extension in my main configuration file in /usr/local/lib/php.ini, like so:

zend_extension = "/usr/local/lib/php/extensions/no-debug-non-zts-20121212/"

But in my Loaded Configuration file in /home/someuser/public_html/php.ini, I had it incorrectly loaded like this:

After fixing that, remote debugging with PhpStorm is working again for me.

As a side note, the first error I saw in PhpStorm was the exact same one the OP mentions, and here is what it looks like:

PhpStorm xdebug server variables error

Cannot accept external Xdebug connection
Cannot evaluate expression 'isset($_SERVER['PHP_IDE_CONFIG'])'

( At first I thought that, because the extension was not loaded properly, PhpStorm was not able to execute PHP code on the server. But now I think PhpStorm only executes php code if you configured an interpreter, which isn't necessary for debugging. For debugging, PhpStorm just needs the xdebug connection and the correct path mappings.)

Later, I found the "Command is not available" error in the xdebug log on my server, which led me to the solution.

Here, by the way, is what I have in my local php.ini for xdebug:

; <- this is the bad line commented!
zend_extension = "/usr/local/lib/php/extensions/no-debug-non-zts-20121212/"


@Emiliano 2017-07-06 20:52:51

I have the same problem and I had configure as zend extension but this issue still happen

@Marius.C 2015-08-06 18:21:49

Another thing is to make sure that you disable any firewall you have and which might block remote connections.

@Buttle Butkus 2016-02-05 01:09:33

For this, I would suggest using ssh tunneling. That way you keep your firewall in place and still can do the remote debugging. It will work even if you don't have access to the firewall/router settings. It was a bit tricky to set up though. You have to pay careful attention to the tutorials.

@Andrew Boxer 2015-07-26 17:01:26

I have recently had the same problem attempting to debug using PHPStorm under nginx and php-fpm, in my case this was not related to the xdebug, nginx or php-fpm config, it was the path mappings in phpstorm that were missing.

Initially PHPStorm will notify you when it cannot map a file on the server to a local source file however if it has a mapping to the first files hit ( normally index.php or some such ) but it cannot map a file used at a later stage ( in my case this was the autoloader in the vendor directory of a project using composer ) then PHPStorm will not be able to debug any further and debugging will stop.

In order to rectify this in PHPStorm go to settings/Languages & Frameworks/PHP/Servers and ensure the root of your project is mapped correctly to it's counterpart directory on the server.

PHPStorm should then be able to map all the files in your project and debugging should continue.

I hope this helps.

@Osama Salama 2015-07-27 13:06:04

Thanks Andrew, This is all true, and became my standard practice when working with new php projects, Cheers

@iainp999 2015-03-25 20:54:36

For anyone else coming to this issue, there is another potential configuration option that you could be missing.

Make sure that you have correctly configured your server to use the correct path mapping between your local and remote files.

For example, if your site root is mounted locally at /home/foo/www/mysite but installed on the server at /www/mysite then you will need to edit your server configuration in PHPStorm to use path mappings (simply enter /www/mysite in the box alongside /home/foo/www/mysite).

@Guerrilla 2015-06-13 15:01:11

It's making me do this for every single file individually, it won't let me just set mapping for the top level folder. Any ideas?

@iainp999 2015-07-09 14:15:46

Hey - just set it at the root folder and all other files should be relative to that.

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