PHP Error Handling: A Complete Beginner-Friendly Guide

Errors are a natural part of developing PHP applications. Proper error handling helps you:

• Debug issues faster

• Prevent exposing sensitive information

• Provide user‑friendly messages

• Log problems for developers

This tutorial explains all essential PHP error handling techniques with examples.

Types of Errors in PHP

Common PHP error types include:

• Parse Error – Syntax issues (missing semicolon, bracket)

• Fatal Error – Script stops (undefined class/function)

• Warning – Non‑fatal problems; script continues

• Notice – Minor issues (undefined variable)

• Exception – Errors thrown using throw and handled by try...catch

🔧 Controlling Error Reporting

Use error_reporting() to show specific types of errors.

<?php
// Show all errors
error_reporting(E_ALL);

// Show warnings & errors only
error_reporting(E_ERROR | E_WARNING);
?>

Display errors (development)

ini_set('display_errors', 1);

Hide errors (production)

ini_set('display_errors', 0);
ini_set('log_errors', 1);

Example: Enable Error Display (Useful for Localhost)

<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);

echo $name; // Notice: undefined variable
?>

Handling Errors Using Try–Catch (Exceptions)

Exceptions allow graceful, controlled error handling.

Example:

<?php
function divide($a, $b) {
    if ($b == 0) {
        throw new Exception("Cannot divide by zero");
    }
    return $a / $b;
}

try {
    echo divide(10, 0);
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}
?>

Handling Database Errors (PDOException)

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=test", "root", "");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    echo "Database Error: " . $e->getMessage();
}
?>

Custom Error Handler Using set_error_handler()

Create your own function to process PHP errors.

<?php
function myErrorHandler($errno, $errstr, $errfile, $errline) {
    $msg = "Error [$errno]: $errstr in $errfile on line $errline";
    error_log($msg);
    echo "Something went wrong. Please try again later.";
    return true; // Prevent default handler
}

set_error_handler("myErrorHandler");

echo $undefinedVar; // Triggers custom handler
?>

Converting Errors to Exceptions

<?php
set_error_handler(function ($errno, $errstr, $errfile, $errline) {
    throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});

try {
    echo $undefinedVar;
} catch (ErrorException $e) {
    echo "Caught exception: " . $e->getMessage();
}
?>

 Logging Errors Manually

<?php
error_log("Custom log entry", 3, __DIR__ . "/app.log");
?>

Useful for debugging API failures, DB errors, etc.

Example: Safe File Read with Error Handling

<?php
function readFileSafe($file) {
    if (!file_exists($file)) {
        throw new Exception("File missing: $file");
    }

    $content = @file_get_contents($file);

    if ($content === false) {
        throw new Exception("Unable to read file: $file");
    }

    return $content;
}

try {
    echo readFileSafe("data.txt");
} catch (Exception $e) {
    error_log($e->getMessage());
    echo "Unable to load file.";
}
?>

Best Practices for PHP Error Handling

• Show all errors in development; hide them in production

• Log errors instead of showing them to users

• Avoid exposing file paths, SQL queries, or stack traces

• Use exceptions for DB queries, APIs, and risky operations

• Always sanitize user input before using it

• Convert PHP errors to exceptions for uniform handling

Summary

You learned:

• Types of PHP errors

• Error reporting and configuration

• Try–catch blocks and exception handling

• Custom error handlers

• Safe file/database handling practices

Proper error handling improves security, performance, and user experience.