How to show or remove warning and error messages in PHP

Managing the display of error and warning messages in PHP is critical for balancing development and production needs. During development, showing these messages can help identify issues. In a production environment, it’s important to control their visibility to avoid exposing sensitive information.

The display and reporting of errors in PHP are managed using the display_errors and error_reporting directives. display_errors controls whether errors are shown to the user, while error_reporting determines the types of errors that are reported. Configuring these directives allows you to customize error handling based on your environment.

In development, you may enable error display to see all issues in real-time. In production, it’s advisable to disable error display but still log errors for security and debugging purposes.

1. Open the PHP configuration file.

   $ sudo vi /etc/php/7.4/apache2/php.ini

   Related: PHP configuration files

2. Locate the display_errors directive.

   ; This directive controls whether or not and where PHP will output errors,
   ; notices and warnings too. Error output is very useful during development, but
   ; it could be very dangerous in production environments. Depending on the code
   ; which is triggering the error, sensitive information could potentially leak
   ; out of your application such as database usernames and passwords or worse.
   ; For production environments, we recommend logging errors rather than
   ; sending them to STDOUT.
   ; Possible Values:
   ;   Off = Do not display any errors
   ;   stderr = Display errors to STDERR (affects only CGI/CLI binaries!)
   ;   On or stdout = Display errors to STDOUT
   ; Default Value: On
   ; Development Value: On
   ; Production Value: Off
   ; http://php.net/display-errors
   display_errors = On

3. Set display_errors to On to enable or Off to disable displaying errors.

   display_errors = Off

   Set the value to On instead to further tune the types of messages to display using error_reporting directive.

4. Locate the error_reporting directive.

   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ; Error handling and logging ;
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   
   ; This directive informs PHP of which errors, warnings and notices you would like
   ; it to take action for. The recommended way of setting values for this
   ; directive is through the use of the error level constants and bitwise
   ; operators. The error level constants are below here for convenience as well as
   ; some common settings and their meanings.
   ; By default, PHP is set to take action on all errors, notices and warnings EXCEPT
   ; those related to E_NOTICE and E_STRICT, which together cover best practices and
   ; recommended coding standards in PHP. For performance reasons, this is the
   ; recommend error reporting setting. Your production server shouldn't be wasting
   ; resources complaining about best practices and coding standards. That's what
   ; development servers and development settings are for.
   ; Note: The php.ini-development file has this setting as E_ALL. This
   ; means it pretty much reports everything which is exactly what you want during
   ; development and early testing.
   ;
   ; Error Level Constants:
   ; E_ALL             - All errors and warnings (includes E_STRICT as of PHP 5.4.0)
   ; E_ERROR           - fatal run-time errors
   ; E_RECOVERABLE_ERROR  - almost fatal run-time errors
   ; E_WARNING         - run-time warnings (non-fatal errors)
   ; E_PARSE           - compile-time parse errors
   ; E_NOTICE          - run-time notices (these are warnings which often result
   ;                     from a bug in your code, but it's possible that it was
   ;                     intentional (e.g., using an uninitialized variable and
   ;                     relying on the fact it is automatically initialized to an
   ;                     empty string)
   ; E_STRICT          - run-time notices, enable to have PHP suggest changes
   ;                     to your code which will ensure the best interoperability
   ;                     and forward compatibility of your code
   ; E_CORE_ERROR      - fatal errors that occur during PHP's initial startup
   ; E_CORE_WARNING    - warnings (non-fatal errors) that occur during PHP's
   ;                     initial startup
   ; E_COMPILE_ERROR   - fatal compile-time errors
   ; E_COMPILE_WARNING - compile-time warnings (non-fatal errors)
   ; E_USER_ERROR      - user-generated error message
   ; E_USER_WARNING    - user-generated warning message
   ; E_USER_NOTICE     - user-generated notice message
   ; E_DEPRECATED      - warn about code that will not work in future versions
   ;                     of PHP
   ; E_USER_DEPRECATED - user-generated deprecation warnings
   ;
   ; Common Values:
   ;   E_ALL (Show all errors, warnings and notices including coding standards.)
   ;   E_ALL & ~E_NOTICE  (Show all errors, except for notices)
   ;   E_ALL & ~E_NOTICE & ~E_STRICT  (Show all errors, except for notices and coding standards warnings.)
   ;   E_COMPILE_ERROR|E_RECOVERABLE_ERROR|E_ERROR|E_CORE_ERROR  (Show only errors)
   ; Default Value: E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED
   ; Development Value: E_ALL
   ; Production Value: E_ALL & ~E_DEPRECATED & ~E_STRICT
   ; http://php.net/error-reporting
   error_reporting = E_ALL

5. Set error_reporting to define which types of errors to reports.

   error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT

6. Restart your web server to apply the changes.

   $ sudo systemctl restart apache2

   Related: How to manage the Apache web server service