How do you handle errors and exceptions in PHP 8, and what changed from earlier versions?

PHP historically had two parallel systems — traditional errors and exceptions — and PHP 7 unified them. Most fatal errors now throw Error, and both Error and Exception implement Throwable.

try {
    $result = $service->process($input);
} catch (ValidationException $e) {
    return $this->badRequest($e->getMessage());
} catch (Throwable $e) {
    $this->logger->error($e->getMessage(), ['exception' => $e]);
    return $this->serverError();
} finally {
    $this->cleanup();
}

What matters in practice:

• Catch Throwable, not Exception, when you want a genuine catch-all — TypeError and DivisionByZeroError are Errors and will slip past Exception.
• Define your own exception types. PaymentDeclinedException lets callers handle one failure differently from another; throwing a generic Exception forces string matching on messages.
• Set an exception handler and an error handler at the application's entry point so nothing escapes unlogged, and convert warnings into ErrorException so they cannot be ignored.
• Never show a stack trace to a user. display_errors off in production, log_errors on.

Note: PHP 8 also made many previously-silent warnings into errors — accessing an undefined array key, for example — which is why an upgrade surfaces bugs that were always there.