ErrorHandlingMiddleware

Catches unhandled throwables from downstream middleware/action dispatch and produces a generic 500 (or mapped) response.

Currently minimal; can be extended to perform content negotiation (HTML/JSON) and structured logging.

Synopsis

class ErrorHandlingMiddleware implements MiddlewareInterface

Implements	MiddlewareInterface
Source	Middleware/ErrorHandlingMiddleware.php

Constructor

__construct()

public function __construct(callable(Throwable $e, ServerRequestInterface $r): void|null $logger = null): mixed

Parameter	Type	Description
$logger	`callable(Throwable $e, ServerRequestInterface $r): void“	“null`

Returns mixed

Methods

Method	Description
process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface	Catches any throwable escaping the rest of the stack and renders it as a response.
renderExceptionResponse(ServerRequestInterface $request, Throwable $e): ResponseInterface	Public helper so Kernel (or other bootstrap code) can render a unified exception response.

process()

public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface

Catches any throwable escaping the rest of the stack and renders it as a response.

Logs a single diagnostic line carrying the exception class, message, throw site, the triggering request, the cause chain and the trace, then hands the exception to ErrorHandlingMiddleware::renderExceptionResponse() for the actual body and status. Nothing propagates out of here, which is the point of its high bootstrap priority: everything ordered inside it is covered.

Middleware that must see error and 404 responses has to be ordered outside this one; after: ErrorHandlingMiddleware places it within the try and it will be skipped whenever an exception is thrown.

Parameter	Type	Description
$request	ServerRequestInterface
$handler	RequestHandlerInterface

Returns ResponseInterface

renderExceptionResponse()

public function renderExceptionResponse(ServerRequestInterface $request, Throwable $e): ResponseInterface

Public helper so Kernel (or other bootstrap code) can render a unified exception response.

Parameter	Type	Description
$request	ServerRequestInterface
$e	Throwable

Returns ResponseInterface