What is the difference between set_error_handler and set_exception_handler in PHP?

set_error_handler intercepts traditional PHP errors (notices, warnings, deprecated) and lets you convert them into exceptions using ErrorException. set_exception_handler catches any uncaught exception or error that bubbles to the top of the call stack. For APIs, use both: set_error_handler to convert errors into exceptions, and set_exception_handler as the ultimate safety net that formats a JSON error response and logs the failure.

How do I customize error responses in Laravel 11+ API applications?

In Laravel 11+, configure exception rendering in bootstrap/app.php using the withExceptions() method. Call $exceptions->render() with a closure that receives the exception and request, then return a JsonResponse. Register handlers from most specific to least specific. Laravel automatically handles ValidationException and AuthenticationException, but you can override them. Always add a Throwable catch-all that returns a generic 500 response and calls report() to log the exception.

How should I handle PDO database exceptions in a PHP API without leaking SQL details?

Catch PDOException specifically, inspect the SQLSTATE code (e.g., 23505 for unique violation, 23503 for foreign key violation) to return meaningful HTTP errors like 409 Conflict. Log the full exception message and query context server-side using Monolog or your framework's logger. Return a generic 'database error' message to the client. Never include raw SQL, table names, or column names in API responses.

What is the recommended JSON error format for PHP APIs?

Use a consistent envelope: {error: {code: 'machine_readable_string', message: 'Human readable description', status: 422}}. For validation errors, add a details field with field-level errors: {error: {code: 'validation_error', message: 'Validation failed', status: 422, details: {email: ['Email is required'], name: ['Name must be at least 2 characters']}}}. This format is easy to parse programmatically and gives clients enough context to display meaningful error messages.

How do I configure Monolog for structured API error logging in PHP?

Create a Logger instance with a StreamHandler pointing to stderr or a file. Set JsonFormatter as the handler's formatter so each log entry is a single JSON line. Use pushProcessor to add request context (request ID, HTTP method, URI, user ID) to every log entry. In Laravel, configure a custom channel in config/logging.php with driver 'monolog', handler StreamHandler, and formatter JsonFormatter. Ship logs to a centralized system like ELK or Datadog for searchability.

PHP API Error Handling Best Practices