Xdebug successfully connects to DBGP clients, but won't stop at breakpoints

Question

I have Xdebug 2.1 installed, and running with PHP 5.2.13. It can successfully connect to multiple DBGP clients (i.e. the xdebug.remote_log shows communication back and forth, and the clients themselves also show the incoming connection), but it doesn't stop at breakpoints. I have tried NetBeans, MacGDBp and also the command-line debugclient bundled with Xdebug.

A typical exchange looks like:

Log opened at 2010-07-20 09:33:17
-> <init xmlns="urn:debugger_protocol_v1" xmlns:xdebug="http://xdebug.org/dbgp/xdebug" fileuri="file:///mnt/hgfs/htdocs/mycompany/index.php" language="PHP" protocol_version="1.0" appid="14371" idekey="macgdbp"><engine version="2.1.0"><![CDATA[Xdebug]]></engine><author><![CDATA[Derick Rethans]]></author><url><![CDATA[http://xdebug.org]]&gt;&lt;/url&gt;&lt;copyright&gt;&lt;![CDATA[Copyright (c) 2002-2010 by Derick Rethans]]></copyright></init>

<- status -i macgdbp
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="http://xdebug.org/dbgp/xdebug" command="status" transaction_id="macgdbp" status="starting" reason="ok"></response>

<- step_into -i macgdbp
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="http://xdebug.org/dbgp/xdebug" command="step_into" transaction_id="macgdbp" status="stopping" reason="ok"></response>

<- status -i macgdbp
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="http://xdebug.org/dbgp/xdebug" command="status" transaction_id="macgdbp" status="stopping" reason="ok"></response>

Log closed at 2010-07-20 09:33:18

NetBeans attempts to set breakpoints, and these are acknowledged by Xdebug:

<- breakpoint_set -i 7 -t line -s enabled -f file:///mnt/hgfs/htdocs/mycompany/index.php -n 9
-> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="http://xdebug.org/dbgp/xdebug" command="breakpoint_set" transaction_id="7" state="enabled" id="139360004"></response>

However, Xdebug still refuses to stop!

Answer 1

This appears to happen if you have have Xdebug loaded as an extension (i.e. extension=xdebug.so) in the PHP config instead of a zend_extension (i.e. zend_extension=/usr/lib/php5/20060613+lfs/xdebug.so).

Make sure that you don't have an extension=xdebug.so line anywhere in your PHP config, even if you're pretty sure you're using zend_extension. For example, if you have zend_extension in /etc/php5/conf.d/xdebug.ini, this may well be superseded by an extension in /etc/php5/apache2/php.ini. If this is the case, nothing will complain, and phpinfo() will dutifully report that Xdebug is loaded! (Xdebug 2.1 does issue a small warning in phpinfo() when loaded as an extension, but previous versions do nothing.)