Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Errors and Logging Configuration Options
Name Default Changeable Changelog
error_reporting NULL PHP_INI_ALL  
display_errors "1" PHP_INI_ALL  
display_startup_errors "0" PHP_INI_ALL  
log_errors "0" PHP_INI_ALL  
log_errors_max_len "1024" PHP_INI_ALL Available since PHP 4.3.0.
ignore_repeated_errors "0" PHP_INI_ALL Available since PHP 4.3.0.
ignore_repeated_source "0" PHP_INI_ALL Available since PHP 4.3.0.
report_memleaks "1" PHP_INI_ALL Available since PHP 4.3.0.
track_errors "0" PHP_INI_ALL  
html_errors "1" PHP_INI_ALL PHP_INI_SYSTEM in PHP <= 4.2.3.
xmlrpc_errors "0" PHP_INI_SYSTEM Available since PHP 4.1.0.
xmlrpc_error_number "0" PHP_INI_ALL Available since PHP 4.1.0.
docref_root "" PHP_INI_ALL Available since PHP 4.3.0.
docref_ext "" PHP_INI_ALL Available since PHP 4.3.2.
error_prepend_string NULL PHP_INI_ALL  
error_append_string NULL PHP_INI_ALL  
error_log NULL PHP_INI_ALL  
For further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

error_reporting integer

Set the error reporting level. The parameter is either an integer representing a bit field, or named constants. The error_reporting levels and constants are described in Predefined Constants, and in php.ini. To set at runtime, use the error_reporting() function. See also the display_errors directive.

PHP 5.3 or later, the default value is E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED. This setting does not show E_NOTICE, E_STRICT and E_DEPRECATED level errors. You may want to show them during development. Prior to PHP 5.3.0, the default value is E_ALL & ~E_NOTICE & ~E_STRICT. In PHP 4 the default value is E_ALL & ~E_NOTICE.


Enabling E_NOTICE during development has some benefits. For debugging purposes: NOTICE messages will warn you about possible bugs in your code. For example, use of unassigned values is warned. It is extremely useful to find typos and to save time for debugging. NOTICE messages will warn you about bad style. For example, $arr[item] is better to be written as $arr['item'] since PHP tries to treat "item" as constant. If it is not a constant, PHP assumes it is a string index for the array.


In PHP 5 a new error level E_STRICT is available. Prior to PHP 5.4.0 E_STRICT was not included within E_ALL, so you would have to explicitly enable this kind of error level in PHP < 5.4.0. Enabling E_STRICT during development has some benefits. STRICT messages provide suggestions that can help ensure the best interoperability and forward compatibility of your code. These messages may include things such as calling non-static methods statically, defining properties in a compatible class definition while defined in a used trait, and prior to PHP 5.3 some deprecated features would issue E_STRICT errors such as assigning objects by reference upon instantiation.

Note: PHP Constants outside of PHP

Using PHP Constants outside of PHP, like in httpd.conf, will have no useful meaning so in such cases the integer values are required. And since error levels will be added over time, the maximum value (for E_ALL) will likely change. So in place of E_ALL consider using a larger value to cover all bit fields from now and well into the future, a numeric value like 2147483647 (includes all errors, not just E_ALL).

display_errors string

This determines whether errors should be printed to the screen as part of the output or if they should be hidden from the user.

Value "stderr" sends the errors to stderr instead of stdout. The value is available as of PHP 5.2.4. In earlier versions, this directive was of type boolean.


This is a feature to support your development and should never be used on production systems (e.g. systems connected to the internet).


Although display_errors may be set at runtime (with ini_set()), it won't have any effect if the script has fatal errors. This is because the desired runtime action does not get executed.

display_startup_errors boolean

Even when display_errors is on, errors that occur during PHP's startup sequence are not displayed. It's strongly recommended to keep display_startup_errors off, except for debugging.

log_errors boolean

Tells whether script error messages should be logged to the server's error log or error_log. This option is thus server-specific.


You're strongly advised to use error logging in place of error displaying on production web sites.

log_errors_max_len integer

Set the maximum length of log_errors in bytes. In error_log information about the source is added. The default is 1024 and 0 allows to not apply any maximum length at all. This length is applied to logged errors, displayed errors and also to $php_errormsg.

When an integer is used, the value is measured in bytes. Shorthand notation, as described in this FAQ, may also be used.
ignore_repeated_errors boolean

Do not log repeated messages. Repeated errors must occur in the same file on the same line unless ignore_repeated_source is set true.

ignore_repeated_source boolean

Ignore source of message when ignoring repeated messages. When this setting is On you will not log errors with repeated messages from different files or sourcelines.

report_memleaks boolean

If this parameter is set to On (the default), this parameter will show a report of memory leaks detected by the Zend memory manager. This report will be send to stderr on Posix platforms. On Windows, it will be send to the debugger using OutputDebugString(), and can be viewed with tools like » DbgView. This parameter only has effect in a debug build, and if error_reporting includes E_WARNING in the allowed list.

track_errors boolean

If enabled, the last error message will always be present in the variable $php_errormsg.

html_errors boolean

Turn off HTML tags in error messages. The new format for HTML errors produces clickable messages that direct the user to a page describing the error or function in causing the error. These references are affected by docref_root and docref_ext.

xmlrpc_errors boolean

Turns off normal error reporting and formats errors as XML-RPC error message.

xmlrpc_error_number integer

Used as the value of the XML-RPC faultCode element.

docref_root string

The new error format contains a reference to a page describing the error or function causing the error. In case of manual pages you can download the manual in your language and set this ini directive to the URL of your local copy. If your local copy of the manual can be reached by "/manual/" you can simply use docref_root=/manual/. Additional you have to set docref_ext to match the fileextensions of your copy docref_ext=.html. It is possible to use external references. For example you can use docref_root=http://manual/en/ or docref_root=" &"

Most of the time you want the docref_root value to end with a slash "/". But see the second example above which does not have nor need it.


This is a feature to support your development since it makes it easy to lookup a function description. However it should never be used on production systems (e.g. systems connected to the internet).

docref_ext string

See docref_root.


The value of docref_ext must begin with a dot ".".

error_prepend_string string

String to output before an error message.

error_append_string string

String to output after an error message.

error_log string

Name of the file where script errors should be logged. The file should be writable by the web server's user. If the special value syslog is used, the errors are sent to the system logger instead. On Unix, this means syslog(3) and on Windows NT it means the event log. The system logger is not supported on Windows 95. See also: syslog(). If this directive is not set, errors are sent to the SAPI error logger. For example, it is an error log in Apache or stderr in CLI. See also error_log().

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User Contributed Notes 5 notes

cjakeman at bcs dot org
5 years ago
<?php ini_set('display_errors', 1); ?>
at the top of your script will not catch any parse errors. A missing ")" or ";" will still lead to a blank page.

This is because the entire script is parsed before any of it is executed. If you are unable to change php.ini and set

display_errors On

then there is a possible solution suggested under error_reporting:

ini_set("display_errors", 1);

[Modified by moderator]

You should also consider setting error_reporting = -1 in your php.ini and display_errors = On if you are in development mode to see all fatal/parse errors or set error_log to your desired file to log errors instead of display_errors in production (this requires log_errors to be turned on).
php dot net at sp-in dot dk
11 hours ago
There does not appear to be a way to set a tag / ident / program for log entries in the ini file when using error_log=syslog.  When I test locally, "apache2" is used.
However, calling openlog() with an ident parameter early in your script (or using an auto_prepend_file) will make PHP use that value for all subsequent log entries. closelog() will restore the original tag.

This can be done for setting facility as well, although the original value does not seem to be restored by closelog().
plonk at xonx dot de
3 years ago
When using PHP with Apache mod_fcgid and "log_errors = On", PHP errors get logged into Apache ErrorLog file with severity "warn". No matter what severity the PHP error itself has, the severity in the Apache log is "warn".
To log PHP errors in the Apache log, use:
LogLevel warn
(or debug, info, notice)
geompse at gmail dot com
3 years ago
Note that if error_log is empty, errors/warnings/notices will be written to stderr (standard error stream), and this may be a problem if you is PHP in CLI.

# test.php

1 as $i);

1 as $i);

ini_set('error_log','/dev/null'); #linux
foreach(1 as $i);

php -f test.php
will output :
: Invalid argument supplied for foreach() in /test.php on line 7 # stdout
PHP WarningInvalid argument supplied for foreach() in /test.php on line 10 # stderr
Warning: Invalid argument supplied for foreach() in /test.php on line 10 # stdout
Warning: Invalid argument supplied for foreach() in /test.php on line 13 # stdout

Errors displayed in the stdout (standard output stream) car be catched with the output buffering functions (ob_start/ob_get_clean) while strerr cannot.
ivanmaz at yandex dot ru
5 years ago
There is a more simple and more correct solution - to use file .htaccess, where you can simply add the following lines:

php_value display_errors 1
php_value display_startup_errors 1
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