PHP handles errors with exceptions caught via try/catch/finally. Proper exception handling means catching specific types, creating meaningful custom exceptions, cleaning up resources, and never exposing internal details to users.
{
= ();
} ( ) {
(->());
} (DatabaseException ) {
();
} ( ) {
();
;
} {
();
}
Catch specific exception types (most specific first), use Throwable as a final catch-all (covers both Error and Exception), and use finally for cleanup that must always run.
// throwing
if ($amount < 0) {
throw new InvalidArgumentException("Amount must be positive, got $amount");
}
// a custom exception for your domain
class InsufficientFundsException extends Exception {
public function __construct(private float $shortfall) {
parent::__construct("Short by $shortfall");
}
public function getShortfall(): float { return $this->shortfall; }
}
throw new InsufficientFundsException(50.0);
Custom exception classes make error handling expressive and let callers catch specific domain errors.
try {
$db->query(...);
} catch (PDOException $e) {
// wrap with context, preserving the original as the "previous" exception
throw new RepositoryException("Failed to load user", 0, $e);
}
The third constructor argument chains the original exception ($e->getPrevious()), preserving the full cause for debugging.
✓ Catch SPECIFIC exceptions, not a blanket Throwable (unless intentionally last)
✓ Don't swallow exceptions silently (empty catch) — log or re-throw
✓ Use finally / proper cleanup for resources (files, connections)
✓ Create meaningful custom exceptions for domain errors
✓ SECURITY: log details internally; show users a generic message (don't leak
stack traces / internal info — display_errors off in production)
Proper exception handling is essential for building robust, reliable, and secure PHP applications.
Understanding the try/catch/finally structure, catching specific exception types (for targeted handling) with Throwable as a final catch-all (covering both Error and Exception in modern PHP), and using finally for guaranteed cleanup is fundamental everyday knowledge.
Beyond the mechanics, the best practices matter: creating meaningful custom exceptions for domain errors makes code expressive and lets callers handle specific failures; exception chaining preserves the root cause for debugging; and crucially, not swallowing exceptions silently (logging or re-throwing instead) prevents hidden failures.
A particularly important point is security: exceptions and errors should be logged internally but never exposed to users (stack traces and internal details leak sensitive information and aid attackers — hence display_errors off in production).
Knowing how to handle exceptions properly — specific catches, custom exceptions, cleanup, chaining, and secure logging rather than exposure — distinguishes robust, professional PHP from fragile code that crashes ungracefully or leaks information, making it important knowledge for building reliable, secure applications.