diff --git a/framework/core/src/Foundation/ErrorHandling/HandledError.php b/framework/core/src/Foundation/ErrorHandling/HandledError.php
index 738ba6da5..55b57d5d7 100644
--- a/framework/core/src/Foundation/ErrorHandling/HandledError.php
+++ b/framework/core/src/Foundation/ErrorHandling/HandledError.php
@@ -13,6 +13,13 @@ namespace Flarum\Foundation\ErrorHandling;
 
 use Throwable;
 
+/**
+ * An error that was caught / interpreted by Flarum's error handling stack.
+ *
+ * Most importantly, such an error has a "type" (which is used to look up
+ * translated error messages and views to render pretty HTML pages) and an
+ * associated HTTP status code for used in rendering HTTP error responses.
+ */
 class HandledError
 {
     private $error;
diff --git a/framework/core/src/Foundation/ErrorHandling/HttpFormatter.php b/framework/core/src/Foundation/ErrorHandling/HttpFormatter.php
index 27a383aed..92473aceb 100644
--- a/framework/core/src/Foundation/ErrorHandling/HttpFormatter.php
+++ b/framework/core/src/Foundation/ErrorHandling/HttpFormatter.php
@@ -16,5 +16,16 @@ use Psr\Http\Message\ServerRequestInterface as Request;
 
 interface HttpFormatter
 {
+    /**
+     * Create an HTTP Response to represent the error we are handling.
+     *
+     * This method receives the error that was caught by Flarum's error handling
+     * stack, along with the current HTTP request instance. It should return an
+     * HTTP response that explains or represents what went wrong.
+     *
+     * @param HandledError $error
+     * @param Request $request
+     * @return Response
+     */
     public function format(HandledError $error, Request $request): Response;
 }
diff --git a/framework/core/src/Foundation/ErrorHandling/JsonApiFormatter.php b/framework/core/src/Foundation/ErrorHandling/JsonApiFormatter.php
index 87e1921ec..bebdf9d15 100644
--- a/framework/core/src/Foundation/ErrorHandling/JsonApiFormatter.php
+++ b/framework/core/src/Foundation/ErrorHandling/JsonApiFormatter.php
@@ -16,6 +16,11 @@ use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
 use Tobscure\JsonApi\Document;
 
+/**
+ * A formatter to render exceptions as valid {JSON:API} error object.
+ *
+ * See https://jsonapi.org/format/1.0/#errors.
+ */
 class JsonApiFormatter implements HttpFormatter
 {
     public function format(HandledError $error, Request $request): Response
diff --git a/framework/core/src/Foundation/ErrorHandling/LogReporter.php b/framework/core/src/Foundation/ErrorHandling/LogReporter.php
index edff300d1..b9344c5c8 100644
--- a/framework/core/src/Foundation/ErrorHandling/LogReporter.php
+++ b/framework/core/src/Foundation/ErrorHandling/LogReporter.php
@@ -13,6 +13,9 @@ namespace Flarum\Foundation\ErrorHandling;
 
 use Psr\Log\LoggerInterface;
 
+/**
+ * Log caught exceptions to a PSR-3 logger instance.
+ */
 class LogReporter implements Reporter
 {
     /**
diff --git a/framework/core/src/Foundation/ErrorHandling/Registry.php b/framework/core/src/Foundation/ErrorHandling/Registry.php
index 45ed5c4ec..d5b0bb9fe 100644
--- a/framework/core/src/Foundation/ErrorHandling/Registry.php
+++ b/framework/core/src/Foundation/ErrorHandling/Registry.php
@@ -14,6 +14,13 @@ namespace Flarum\Foundation\ErrorHandling;
 use Flarum\Foundation\KnownError;
 use Throwable;
 
+/**
+ * Flarum's central registry of known error types.
+ *
+ * It knows how to deal with errors raised both within Flarum's core and outside
+ * of it, map them to error "types" and how to determine appropriate HTTP status
+ * codes for them.
+ */
 class Registry
 {
     private $statusMap;
@@ -27,6 +34,18 @@ class Registry
         $this->handlerMap = $handlerMap;
     }
 
+    /**
+     * Map exceptions to handled errors.
+     *
+     * This can map internal ({@see \Flarum\Foundation\KnownError}) as well as
+     * external exceptions (any classes inheriting from \Throwable) to instances
+     * of {@see \Flarum\Foundation\ErrorHandling\HandledError}.
+     *
+     * Even for unknown exceptions, a generic fallback will always be returned.
+     *
+     * @param Throwable $error
+     * @return HandledError
+     */
     public function handle(Throwable $error): HandledError
     {
         return $this->handleKnownTypes($error)
diff --git a/framework/core/src/Foundation/ErrorHandling/ViewFormatter.php b/framework/core/src/Foundation/ErrorHandling/ViewFormatter.php
index 12664bbd2..d40ca2ca4 100644
--- a/framework/core/src/Foundation/ErrorHandling/ViewFormatter.php
+++ b/framework/core/src/Foundation/ErrorHandling/ViewFormatter.php
@@ -18,6 +18,17 @@ use Psr\Http\Message\ServerRequestInterface as Request;
 use Symfony\Component\Translation\TranslatorInterface;
 use Zend\Diactoros\Response\HtmlResponse;
 
+/**
+ * A formatter for turning caught exceptions into "pretty" HTML error pages.
+ *
+ * For certain known error types, we display pages with dedicated information
+ * relevant to this class of error, e.g. a page with a search form for HTTP 404
+ * "Not Found" errors. We look for templates in the `views/error` directory.
+ *
+ * If no specific template exists, a generic "Something went wrong" page will be
+ * displayed, optionally enriched with a more specific error message if found in
+ * the translation files.
+ */
 class ViewFormatter implements HttpFormatter
 {
     /**
diff --git a/framework/core/src/Foundation/ErrorHandling/WhoopsFormatter.php b/framework/core/src/Foundation/ErrorHandling/WhoopsFormatter.php
index 549ea8a0a..7f2d26456 100644
--- a/framework/core/src/Foundation/ErrorHandling/WhoopsFormatter.php
+++ b/framework/core/src/Foundation/ErrorHandling/WhoopsFormatter.php
@@ -15,6 +15,15 @@ use Franzl\Middleware\Whoops\WhoopsRunner;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
 
+/**
+ * Handle errors using the Whoops error handler for debugging.
+ *
+ * Proper status codes for all known error types are returned. In addition,
+ * content negotiation is performed to return proper responses in various
+ * environments such as HTML frontends or API backends.
+ *
+ * Should only be used in debug mode (because Whoops may expose sensitive data).
+ */
 class WhoopsFormatter implements HttpFormatter
 {
     public function format(HandledError $error, Request $request): Response
diff --git a/framework/core/src/Http/Middleware/HandleErrors.php b/framework/core/src/Http/Middleware/HandleErrors.php
index 470c379fd..d423d653c 100644
--- a/framework/core/src/Http/Middleware/HandleErrors.php
+++ b/framework/core/src/Http/Middleware/HandleErrors.php
@@ -19,6 +19,13 @@ use Psr\Http\Server\MiddlewareInterface as Middleware;
 use Psr\Http\Server\RequestHandlerInterface as Handler;
 use Throwable;
 
+/**
+ * Catch exceptions thrown in a PSR-15 middleware stack and handle them safely.
+ *
+ * All errors will be rendered using the provided formatter. In addition,
+ * unknown errors will be passed on to one or multiple
+ * {@see \Flarum\Foundation\ErrorHandling\Reporter} instances.
+ */
 class HandleErrors implements Middleware
 {
     /**