PHP Manual: Generates a user-level error/warning/notice message

Description

true trigger_error(string $message, int $error_level = E_USER_NOTICE)

Used to trigger a user error condition, it can be used in conjunction with the built-in error handler, or with a user defined function that has been set as the new error handler (set_error_handler).

This function is useful when you need to generate a particular response to an exception at runtime.

Parameters

message: The designated error message for this error. It's limited to 1024 bytes in length. Any additional characters beyond 1024 bytes will be truncated.
error_level: The designated error type for this error. It only works with the E_USER_* family of constants, and will default to E_USER_NOTICE.

Warning
Passing E_USER_ERROR as the error_level is now deprecated. Throw an Exception or call exit instead.

Return Values

Always returns true.

Errors/Exceptions

This function throws a ValueError if error_level is not one of E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE, E_USER_DEPRECATED.

Changelog

Version	Description
8.4.0	Passing `E_USER_ERROR` as the `error_level` is now deprecated. Throw an Exception or call exit instead.
8.4.0	The function now has a return type of true instead of bool.
8.0.0	The function now throws a ValueError if an invalid `error_level` is specified. Previously, it returned `false`.

Examples

Example #1 trigger_error example

See set_error_handler for a more extensive example.

<?php
$password = $_POST['password'] ?? '';
if ($password === '') {
  trigger_error("Using an empty password is unsafe", E_USER_WARNING);
}
$hash = password_hash($password, PASSWORD_DEFAULT);
?>

Notes

Warning

HTML entities in message are not escaped. Use htmlentities on the message if the error is to be displayed in a browser.

trigger_error