How to remove warning and error messages in PHP

Error warnings for PHP are helpful during development, where you can use them for debugging. Showing the same errors and warnings in a production environment could pose a security risk as it could expose sensitive and exploitable information about the system.

Warning and error reporting in PHP are configured via the display_error error_reporting directives. display_error defines if errors are displayed at all, while error_reporting allows you to specify the type or level of errors to show.

1. Open PHP configuration file using your preferred text editor.

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

   Related: PHP configuration files

2. Search for display_error 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 the value to Off if you don't want to see any error or warning messages at all.

   display_errors = Off

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

4. Search for 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 values to the types of messages to display.

   error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT

6. Restart your web server for changes to take effect.

   $ sudo systemctl restart apache2

   Related: How to manage Apache service