CascadiaPHP 2024

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 INI_ALL  
display_errors "1" INI_ALL  
display_startup_errors "1" INI_ALL Prior to PHP 8.0.0, the default value was "0".
log_errors "0" INI_ALL  
log_errors_max_len "1024" INI_ALL Had no effect as of PHP 8.0.0, removed as of PHP 8.1.0.
ignore_repeated_errors "0" INI_ALL  
ignore_repeated_source "0" INI_ALL  
report_memleaks "1" INI_ALL  
track_errors "0" INI_ALL Deprecated as of PHP 7.2.0, removed as of PHP 8.0.0.
html_errors "1" INI_ALL  
xmlrpc_errors "0" INI_SYSTEM  
xmlrpc_error_number "0" INI_ALL  
docref_root "" INI_ALL  
docref_ext "" INI_ALL  
error_prepend_string NULL INI_ALL  
error_append_string NULL INI_ALL  
error_log NULL INI_ALL  
error_log_mode 0o644 INI_ALL Available as of PHP 8.2.0
syslog.facility "LOG_USER" INI_SYSTEM Available as of PHP 7.3.0.
syslog.filter "no-ctrl" INI_ALL Available as of PHP 7.3.0.
syslog.ident "php" INI_SYSTEM Available as of PHP 7.3.0.
For further details and definitions of the INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

error_reporting int

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.

The default value is E_ALL.

Prior to PHP 8.0.0, the default value was: E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED. This means diagnostics of level E_NOTICE, E_STRICT and E_DEPRECATED were not shown.

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 int 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.


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 bool

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 bool

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 int

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, but not to explicitly called functions such as error_log().

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

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 bool

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 bool

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 sent to stderr on Posix platforms. On Windows, it will be sent 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 bool

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

html_errors bool

If enabled, error messages will include HTML tags. The 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.

If disabled, error message will be solely plain text.

xmlrpc_errors bool

If enabled, turns off normal error reporting and formats errors as XML-RPC error message.

xmlrpc_error_number int

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. Only used when the error message is displayed on screen. The main purpose is to be able to prepend additional HTML markup to the error message.

error_append_string string

String to output after an error message. Only used when the error message is displayed on screen. The main purpose is to be able to append additional HTML markup to the 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 it means the event log. 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().

error_log_mode int

File mode for the file described set in error_log.

syslog.facility string

Specifies what type of program is logging the message. Only effective if error_log is set to "syslog".

syslog.filter string

Specifies the filter type to filter the logged messages. Allowed characters are passed unmodified; all others are written in their hexadecimal representation prefixed with \x.

  • all – the logged string will be split at newline characters, and all characters are passed unaltered
  • ascii – the logged string will be split at newline characters, and any non-printable 7-bit ASCII characters will be escaped
  • no-ctrl – the logged string will be split at newline characters, and any non-printable characters will be escaped
  • raw – all characters are passed to the system logger unaltered, without splitting at newlines (identical to PHP before 7.3)
This setting will affect logging via error_log set to "syslog" and calls to syslog().


The raw filter type is available as of PHP 7.3.8 and PHP 7.4.0.

This directive is not supported on Windows.
syslog.ident string

Specifies the ident string which is prepended to every message. Only effective if error_log is set to "syslog".

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User Contributed Notes 2 notes

cjakeman at bcs dot org
15 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).
ohcc at 163 dot com
7 years ago
If you set the error_log directive to a relative path, it is a path relative to the document root rather than php's containing folder.
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