Debugging: Difference between revisions

Latest revision as of 16:09, 7 April 2015

Debugging messages can be enabled by an administrator in Administration > Site administration > Development > Debugging.

Debugging messages are intended to help diagnose problems and/or help Moodle developers. If you have a problem with your Moodle site and ask for help in a Moodle.org forum, a developer may ask you to turn debug messages on, in order to locate the cause of the problem. By default Moodle does not show any error messages at all. If you are having problems (e.g. blank screens or incomplete screens) turning on debugging is usually the first thing to try.

Debugging settings

Here are the settings on the Debugging page:

Debug messages

The default is none, your choices are:

NONE: Do not show any errors or warnings (Default)
ALL: Show all reasonable PHP debug messages
MINIMAL: Show only fatal errors
NORMAL: Show warnings, errors and notices
DEVELOPER: extra Moodle debug messages for developers

There is rarely any advantage in going to Developer level, unless you are a developer, in which case it is strongly recommended.

Once you have got the error message, and copied and pasted it somewhere. HIGHLY RECOMMENDED to turn Debug back to NONE. Debug messages can give clues to a hacker as to the setup of your site.

Display debug messages

There is an option to choose whether to display error messages or simply record them in the server logs.

Debug email sending

Determines whether or not to enable verbose debug information during sending of email messages to SMTP server.

Performance info

The Performance info option determines whether performance info will be included in the footer of the standard theme (and some other themes). Performance info includes the time for the page to load, the amount of memory used to generate the page, cpu usage, load, and the record cache hit/miss ration.

If you add define('MDL_PERF', true); define('MDL_PERFDB', true); define('MDL_PERFTOLOG', true); define('MDL_PERFTOFOOT', true); to your config.php file, then it will also count database queries. (This has to be in config.php, because Moodle starts doing DB queries before it loads the config information in the database!

Show origin of language strings

Helps with translation and also with Language customization. Sometimes ?strings=1 should be added; other times &strings=1. See the Wikipedia article Query string for details.

Show validator links

Be careful, read the warning.

Show page information

To show page information printed in the page footer.

What to do if you cannot get to the admin screens

If the error is stopping you even getting to the admin screens to turn on debugging, then you can set the debugging setting manually.

Try typing the URL directly

The debug settings are at the URL http://.../admin/settings.php?section=debugging on your server. Sometimes that URL will work, even though the pages you need to go to get there (for example the site front page) do not. So it is worth trying to enter that URL directly.

In config.php

In config.php you can uncomment lines (delete the // at the start of the line) under Section 7 to enable debugging for all or just specific users:

//========================================================================= // 7. SETTINGS FOR DEVELOPMENT SERVERS - not intended for production use!!! //========================================================================= // // Force a debugging mode regardless the settings in the site administration // @error_reporting(E_ALL | E_STRICT); // NOT FOR PRODUCTION SERVERS! // @ini_set('display_errors', '1'); // NOT FOR PRODUCTION SERVERS! // $CFG->debug = (E_ALL | E_STRICT); // === DEBUG_DEVELOPER - NOT FOR PRODUCTION SERVERS! // $CFG->debugdisplay = 1; // NOT FOR PRODUCTION SERVERS! // // You can specify a comma separated list of user ids that that always see // debug messages, this overrides the debug flag in $CFG->debug and $CFG->debugdisplay // for these users only. // $CFG->debugusers = '2';

Remember to comment those lines again (reinsert the // at the start of the line) when you have finished diagnosing your problem.

NOTE 1: do not try to modify the config database table directly, it will not work because the values are cached in MUC.

NOTE 2: if you find your config.php does not have the above settings (you have a cut down approx 30 lines config.php) look for a "config-dist.php" file that contains the full details. I would suggest transferring your details in the current config.php file you have into the full config file and renaming that one to "config.php".

@@ Line 1: / Line 1: @@
-Location: ''Administration > Server > Debugging''
+{{Developer tools}}
+Debugging messages can be enabled by an administrator in ''Administration > Site administration > Development > Debugging''.
 Debugging messages are intended to help diagnose problems and/or help Moodle developers. If you have a problem with your Moodle site and ask for help in a Moodle.org forum, a developer may ask you to turn debug messages on, in order to locate the cause of the problem. By default Moodle does not show any error messages at all. If you are having problems (e.g. blank screens or incomplete screens) turning on debugging is usually the first thing to try.
-==How to turn on debugging==
+==Debugging settings==
+Here are the settings on the Debugging page:
-Go into the admin screens, and look under Administration > Server > Debugging. Set the '''Debug messages''' to '''ALL''', and '''Display debug messages''' to '''Yes'''.
+===Debug messages===
+The default is none, your choices are:
-There is rarely any advantage in going to Developer level.
+;NONE : Do not show any errors or warnings (Default)
+;ALL : Show all reasonable PHP debug messages
+;MINIMAL : Show only fatal errors
+;NORMAL : Show warnings, errors and notices
+;DEVELOPER : extra Moodle debug messages for developers
-Once you have got the error message, and copied and pasted it somewhere, you are recommended to turn debugging back off again.
+There is rarely any advantage in going to Developer level, unless you are a developer, in which case it is strongly recommended.
-==Debug messages==
+Once you have got the error message, and copied and pasted it somewhere.  HIGHLY RECOMMENDED to turn Debug back to NONE. Debug messages can give clues to a hacker as to the setup of your site.
-{{Moodle 1.7}}From Moodle 1.7 onwards, further options are provided for controlling how to handle PHP error messages. The administrator can select the types of error messages to be displayed or logged.
+===Display debug messages===
-The options for debugging include:
-* NONE: Do not show any errors or warnings
-* MINIMAL: Show only fatal errors
-* NORMAL: Show errors, warnings and notices
-* ALL: Show all reasonable PHP debug messages. When you want to find the cause of a problem with your site, this is probably best the setting to use.
-* DEVELOPER: extra Moodle debug messages for developers - If you turn this on, then PHP's error_reporting will be increased so that more warnings are printed.  This is almost essential for developers, but not very helpful for anyone else.
-==Display debug messages==
 There is an option to choose whether to display error messages or simply record them in the server logs.
-==Debug email sending==
+===Debug email sending===
 Determines whether or not to enable verbose debug information during sending of email messages to SMTP server.
-==Performance info==
+===Performance info===
 The Performance info option determines whether performance info will be included in the footer of the standard theme (and some other themes). Performance info includes the time for the page to load, the amount of memory used to generate the page, cpu usage, load, and the record cache hit/miss ration.
@@ Line 42: / Line 40: @@
 </code>
 to your config.php file, then it will also count database queries. (This has to be in config.php, because Moodle starts doing DB queries before it loads the config information in the database!
+===Show origin of language strings===
+Helps with [[:dev:Translation|translation]] and also with [[Language customization]]. Sometimes <code>?strings=1</code> should be added; other times <code>&strings=1</code>. See the Wikipedia article [http://en.wikipedia.org/wiki/Query_string Query string] for details.
+===Show validator links===
+Be careful, read the warning.
+===Show page information===
+To show page information printed in the page footer.
 ==What to do if you cannot get to the admin screens==
@@ Line 49: / Line 57: @@
 ===Try typing the URL directly===
-The debug settings are at the URL <code><nowiki>http://.../admin/settings.php?section=debugging</nowiki></code> on your server. Sometimes that URL will work, even though the pages you need to go to to get there (for example the site front page) do not. So it is worth trying to enter that URL directly.
+The debug settings are at the URL <code><nowiki>http://.../admin/settings.php?section=debugging</nowiki></code> on your server. Sometimes that URL will work, even though the pages you need to go to get there (for example the site front page) do not. So it is worth trying to enter that URL directly.
 ===In config.php===
-In moodle/config.php you can add the lines:
+In [[Configuration file|config.php]] you can uncomment lines (delete the // at the start of the line) under Section 7 to enable debugging for all or just specific users:
-<code php>
-$CFG->debug = 2047;
-$CFG->debugdisplay = 1;
-</code>
-Or even more debugging messages:
 <code php>
-$CFG->debug = 6143;
+//=========================================================================
-$CFG->debugdisplay = 1;
+// 7. SETTINGS FOR DEVELOPMENT SERVERS - not intended for production use!!!
-</code>
+//=========================================================================
+//
-Remember to remove those lines again when you have finished diagnosing your problem.
+// Force a debugging mode regardless the settings in the site administration
+// @error_reporting(E_ALL | E_STRICT);   // NOT FOR PRODUCTION SERVERS!
-===In the database===
+// @ini_set('display_errors', '1');         // NOT FOR PRODUCTION SERVERS!
+// $CFG->debug = (E_ALL | E_STRICT);   // === DEBUG_DEVELOPER - NOT FOR PRODUCTION SERVERS!
-Using a tool like phpMyAdmin, execute the following SQL commands:
+// $CFG->debugdisplay = 1;              // NOT FOR PRODUCTION SERVERS!
+//
-<code sql>
+// You can specify a comma separated list of user ids that that always see
-UPDATE mdl_config SET value = 2047 WHERE name = 'debug';
+// debug messages, this overrides the debug flag in $CFG->debug and $CFG->debugdisplay
-UPDATE mdl_config SET value = 1 WHERE name = 'debugdisplay';
+// for these users only.
+// $CFG->debugusers = '2';
 </code>
-To turn it back off, use the admin screens, or the commands:
+Remember to comment those lines again (reinsert the // at the start of the line) when you have finished diagnosing your problem.
-<code sql>
+'''NOTE 1''': do not try to modify the config database table directly, it will not work because the values are cached in MUC.
-UPDATE mdl_config SET value = 0 WHERE name = 'debug';
-UPDATE mdl_config SET value = 0 WHERE name = 'debugdisplay';
-</code>
-(If you use a different database prefix, you will need to adjust those commands accordingly.)
+'''NOTE 2''': if you find your config.php does not have the above settings (you have a cut down approx 30 lines config.php) look for a "config-dist.php" file that contains the full details. I would suggest transferring your details in the current config.php file you have into the full config file and renaming that one to "config.php".
 ==See also==
-* Using Moodle [http://moodle.org/mod/forum/discuss.php?d=91031 Debugging Turned on to Developer Mode on 1.8.2] forum discussion including instructions on how to turn debugging off
+* Developers can also use [http://xdebug.org/ XDEBUG] (Installed as a module on the Apache server) to further dig into the code, step by step using an [http://xdebug.org/docs/remote XDEBUG client application]. Probably, as part of their favorite IDE. For example: [http://php.netbeans.org/ NetBeans], [http://www.jetbrains.com/phpstorm/ phpStorm] or...
-[[Category:Administrator]]
+[[es:Depuración]]
+[[fr:Débogage]]

Documentation