diff --git a/src/Subscription/Engine/DefaultSubscriptionEngine.php b/src/Subscription/Engine/DefaultSubscriptionEngine.php
index c1fbddd9b..121c82ad9 100644
--- a/src/Subscription/Engine/DefaultSubscriptionEngine.php
+++ b/src/Subscription/Engine/DefaultSubscriptionEngine.php
@@ -36,7 +36,7 @@ public function __construct(
     ) {
     }
 
-    public function setup(SubscriptionEngineCriteria|null $criteria = null, bool $skipBooting = false): void
+    public function setup(SubscriptionEngineCriteria|null $criteria = null, bool $skipBooting = false): Result
     {
         $criteria ??= new SubscriptionEngineCriteria();
 
@@ -47,19 +47,22 @@ public function setup(SubscriptionEngineCriteria|null $criteria = null, bool $sk
         $this->discoverNewSubscriptions();
         $this->retrySubscriptions($criteria);
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
                 status: [Status::New],
             ),
-            function (array $subscriptions) use ($skipBooting): void {
+            function (array $subscriptions) use ($skipBooting): Result {
                 if (count($subscriptions) === 0) {
                     $this->logger?->info('Subscription Engine: No subscriptions to setup, finish setup.');
 
-                    return;
+                    return new Result();
                 }
 
+                /** @var list<Error> $errors */
+                $errors = [];
+
                 $latestIndex = $this->latestIndex();
 
                 foreach ($subscriptions as $subscription) {
@@ -118,8 +121,16 @@ function (array $subscriptions) use ($skipBooting): void {
                         ));
 
                         $this->handleError($subscription, $e);
+
+                        $errors[] = new Error(
+                            $subscription->id(),
+                            $e->getMessage(),
+                            $e,
+                        );
                     }
                 }
+
+                return new Result($errors);
             },
         );
     }
@@ -127,7 +138,7 @@ function (array $subscriptions) use ($skipBooting): void {
     public function boot(
         SubscriptionEngineCriteria|null $criteria = null,
         int|null $limit = null,
-    ): void {
+    ): ProcessedResult {
         $criteria ??= new SubscriptionEngineCriteria();
 
         $this->logger?->info(
@@ -137,19 +148,22 @@ public function boot(
         $this->discoverNewSubscriptions();
         $this->retrySubscriptions($criteria);
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
                 status: [Status::Booting],
             ),
-            function ($subscriptions) use ($limit): void {
+            function ($subscriptions) use ($limit): ProcessedResult {
                 if (count($subscriptions) === 0) {
                     $this->logger?->info('Subscription Engine: No subscriptions in booting status, finish booting.');
 
-                    return;
+                    return new ProcessedResult(0);
                 }
 
+                /** @var list<Error> $errors */
+                $errors = [];
+
                 $startIndex = $this->lowestSubscriptionPosition($subscriptions);
 
                 $this->logger?->debug(
@@ -192,7 +206,13 @@ function ($subscriptions) use ($limit): void {
                                 continue;
                             }
 
-                            $this->handleMessage($index, $message, $subscription);
+                            $error = $this->handleMessage($index, $message, $subscription);
+
+                            if (!$error) {
+                                continue;
+                            }
+
+                            $errors[] = $error;
                         }
 
                         $messageCounter++;
@@ -212,7 +232,9 @@ function ($subscriptions) use ($limit): void {
                                 ),
                             );
 
-                            return;
+                            return new ProcessedResult(
+                                $messageCounter,
+                            );
                         }
                     }
                 } finally {
@@ -258,6 +280,11 @@ function ($subscriptions) use ($limit): void {
                 }
 
                 $this->logger?->info('Subscription Engine: Finish booting.');
+
+                return new ProcessedResult(
+                    $messageCounter,
+                    $errors,
+                );
             },
         );
     }
@@ -265,7 +292,7 @@ function ($subscriptions) use ($limit): void {
     public function run(
         SubscriptionEngineCriteria|null $criteria = null,
         int|null $limit = null,
-    ): void {
+    ): ProcessedResult {
         $criteria ??= new SubscriptionEngineCriteria();
 
         $this->logger?->info('Subscription Engine: Start processing.');
@@ -274,19 +301,22 @@ public function run(
         $this->markDetachedSubscriptions($criteria);
         $this->retrySubscriptions($criteria);
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
                 status: [Status::Active],
             ),
-            function (array $subscriptions) use ($limit): void {
+            function (array $subscriptions) use ($limit): ProcessedResult {
                 if (count($subscriptions) === 0) {
                     $this->logger?->info('Subscription Engine: No subscriptions to process, finish processing.');
 
-                    return;
+                    return new ProcessedResult(0);
                 }
 
+                /** @var list<Error> $errors */
+                $errors = [];
+
                 $startIndex = $this->lowestSubscriptionPosition($subscriptions);
 
                 $this->logger?->debug(
@@ -328,12 +358,21 @@ function (array $subscriptions) use ($limit): void {
                                 continue;
                             }
 
-                            $this->handleMessage($index, $message, $subscription);
+                            $error = $this->handleMessage($index, $message, $subscription);
+
+                            if (!$error) {
+                                continue;
+                            }
+
+                            $errors[] = $error;
                         }
 
                         $messageCounter++;
 
-                        $this->logger?->debug(sprintf('Subscription Engine: Current event stream position: %s', $index));
+                        $this->logger?->debug(sprintf(
+                            'Subscription Engine: Current event stream position: %s',
+                            $index,
+                        ));
 
                         if ($limit !== null && $messageCounter >= $limit) {
                             $this->logger?->info(
@@ -343,7 +382,7 @@ function (array $subscriptions) use ($limit): void {
                                 ),
                             );
 
-                            return;
+                            return new ProcessedResult($messageCounter, $errors);
                         }
                     }
                 } finally {
@@ -385,11 +424,13 @@ function (array $subscriptions) use ($limit): void {
                         $endIndex,
                     ),
                 );
+
+                return new ProcessedResult($messageCounter, $errors);
             },
         );
     }
 
-    public function teardown(SubscriptionEngineCriteria|null $criteria = null): void
+    public function teardown(SubscriptionEngineCriteria|null $criteria = null): Result
     {
         $criteria ??= new SubscriptionEngineCriteria();
 
@@ -397,13 +438,16 @@ public function teardown(SubscriptionEngineCriteria|null $criteria = null): void
 
         $this->logger?->info('Subscription Engine: Start teardown detached subscriptions.');
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
                 status: [Status::Detached],
             ),
-            function (array $subscriptions): void {
+            function (array $subscriptions): Result {
+                /** @var list<Error> $errors */
+                $errors = [];
+
                 foreach ($subscriptions as $subscription) {
                     $subscriber = $this->subscriber($subscription->id());
 
@@ -451,6 +495,13 @@ function (array $subscriptions): void {
                                 $e->getMessage(),
                             ),
                         );
+
+                        $errors[] = new Error(
+                            $subscription->id(),
+                            $e->getMessage(),
+                            $e,
+                        );
+
                         continue;
                     }
 
@@ -465,22 +516,27 @@ function (array $subscriptions): void {
                 }
 
                 $this->logger?->info('Subscription Engine: Finish teardown.');
+
+                return new Result($errors);
             },
         );
     }
 
-    public function remove(SubscriptionEngineCriteria|null $criteria = null): void
+    public function remove(SubscriptionEngineCriteria|null $criteria = null): Result
     {
         $criteria ??= new SubscriptionEngineCriteria();
 
         $this->discoverNewSubscriptions();
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
             ),
-            function (array $subscriptions): void {
+            function (array $subscriptions): Result {
+                /** @var list<Error> $errors */
+                $errors = [];
+
                 foreach ($subscriptions as $subscription) {
                     $subscriber = $this->subscriber($subscription->id());
 
@@ -519,6 +575,12 @@ function (array $subscriptions): void {
                                 $e->getMessage(),
                             ),
                         );
+
+                        $errors[] = new Error(
+                            $subscription->id(),
+                            $e->getMessage(),
+                            $e,
+                        );
                     }
 
                     $this->subscriptionStore->remove($subscription);
@@ -527,17 +589,19 @@ function (array $subscriptions): void {
                         sprintf('Subscription Engine: Subscription "%s" removed.', $subscription->id()),
                     );
                 }
+
+                return new Result($errors);
             },
         );
     }
 
-    public function reactivate(SubscriptionEngineCriteria|null $criteria = null): void
+    public function reactivate(SubscriptionEngineCriteria|null $criteria = null): Result
     {
         $criteria ??= new SubscriptionEngineCriteria();
 
         $this->discoverNewSubscriptions();
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
@@ -548,14 +612,16 @@ public function reactivate(SubscriptionEngineCriteria|null $criteria = null): vo
                     Status::Finished,
                 ],
             ),
-            function (array $subscriptions): void {
-                /** @var Subscription $subscription */
+            function (array $subscriptions): Result {
                 foreach ($subscriptions as $subscription) {
                     $subscriber = $this->subscriber($subscription->id());
 
                     if (!$subscriber) {
                         $this->logger?->debug(
-                            sprintf('Subscription Engine: Subscriber for "%s" not found, skipped.', $subscription->id()),
+                            sprintf(
+                                'Subscription Engine: Subscriber for "%s" not found, skipped.',
+                                $subscription->id(),
+                            ),
                         );
 
                         continue;
@@ -587,17 +653,19 @@ function (array $subscriptions): void {
                         $subscription->id(),
                     ));
                 }
+
+                return new Result();
             },
         );
     }
 
-    public function pause(SubscriptionEngineCriteria|null $criteria = null): void
+    public function pause(SubscriptionEngineCriteria|null $criteria = null): Result
     {
         $criteria ??= new SubscriptionEngineCriteria();
 
         $this->discoverNewSubscriptions();
 
-        $this->findForUpdate(
+        return $this->findForUpdate(
             new SubscriptionCriteria(
                 ids: $criteria->ids,
                 groups: $criteria->groups,
@@ -607,14 +675,17 @@ public function pause(SubscriptionEngineCriteria|null $criteria = null): void
                     Status::Error,
                 ],
             ),
-            function (array $subscriptions): void {
+            function (array $subscriptions): Result {
                 /** @var Subscription $subscription */
                 foreach ($subscriptions as $subscription) {
                     $subscriber = $this->subscriber($subscription->id());
 
                     if (!$subscriber) {
                         $this->logger?->debug(
-                            sprintf('Subscription Engine: Subscriber for "%s" not found, skipped.', $subscription->id()),
+                            sprintf(
+                                'Subscription Engine: Subscriber for "%s" not found, skipped.',
+                                $subscription->id(),
+                            ),
                         );
 
                         continue;
@@ -629,6 +700,8 @@ function (array $subscriptions): void {
                         $subscription->id(),
                     ));
                 }
+
+                return new Result();
             },
         );
     }
@@ -648,7 +721,7 @@ public function subscriptions(SubscriptionEngineCriteria|null $criteria = null):
         );
     }
 
-    private function handleMessage(int $index, Message $message, Subscription $subscription): void
+    private function handleMessage(int $index, Message $message, Subscription $subscription): Error|null
     {
         $subscriber = $this->subscriber($subscription->id());
 
@@ -670,7 +743,7 @@ private function handleMessage(int $index, Message $message, Subscription $subsc
                 ),
             );
 
-            return;
+            return null;
         }
 
         try {
@@ -690,7 +763,11 @@ private function handleMessage(int $index, Message $message, Subscription $subsc
 
             $this->handleError($subscription, $e);
 
-            return;
+            return new Error(
+                $subscription->id(),
+                $e->getMessage(),
+                $e,
+            );
         }
 
         $subscription->changePosition($index);
@@ -704,6 +781,8 @@ private function handleMessage(int $index, Message $message, Subscription $subsc
                 $message->event()::class,
             ),
         );
+
+        return null;
     }
 
     private function subscriber(string $subscriberId): SubscriberAccessor|null
@@ -846,20 +925,27 @@ private function lowestSubscriptionPosition(array $subscriptions): int
         return $min;
     }
 
-    /** @param Closure(list<Subscription>):void $closure */
-    private function findForUpdate(SubscriptionCriteria $criteria, Closure $closure): void
+    /**
+     * @param Closure(list<Subscription>):T $closure
+     *
+     * @return T
+     *
+     * @template T
+     */
+    private function findForUpdate(SubscriptionCriteria $criteria, Closure $closure): mixed
     {
         if (!$this->subscriptionStore instanceof LockableSubscriptionStore) {
-            $closure($this->subscriptionStore->find($criteria));
-
-            return;
+            return $closure($this->subscriptionStore->find($criteria));
         }
 
-        $this->subscriptionStore->inLock(function () use ($closure, $criteria): void {
-            $subscriptions = $this->subscriptionStore->find($criteria);
+        return $this->subscriptionStore->inLock(
+            /** @return T */
+            function () use ($closure, $criteria): mixed {
+                $subscriptions = $this->subscriptionStore->find($criteria);
 
-            $closure($subscriptions);
-        });
+                return $closure($subscriptions);
+            },
+        );
     }
 
     private function handleError(Subscription $subscription, Throwable $throwable): void
diff --git a/src/Subscription/Engine/Error.php b/src/Subscription/Engine/Error.php
new file mode 100644
index 000000000..c28021a6a
--- /dev/null
+++ b/src/Subscription/Engine/Error.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Subscription\Engine;
+
+use Throwable;
+
+final class Error
+{
+    public function __construct(
+        public readonly string $subscriptionId,
+        public readonly string $message,
+        public readonly Throwable $throwable,
+    ) {
+    }
+}
diff --git a/src/Subscription/Engine/ProcessedResult.php b/src/Subscription/Engine/ProcessedResult.php
new file mode 100644
index 000000000..ae3c27190
--- /dev/null
+++ b/src/Subscription/Engine/ProcessedResult.php
@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Subscription\Engine;
+
+final class ProcessedResult
+{
+    /** @param list<Error> $errors */
+    public function __construct(
+        public readonly int $processedMessages,
+        public readonly array $errors = [],
+    ) {
+    }
+}
diff --git a/src/Subscription/Engine/Result.php b/src/Subscription/Engine/Result.php
new file mode 100644
index 000000000..d644bb17d
--- /dev/null
+++ b/src/Subscription/Engine/Result.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Subscription\Engine;
+
+final class Result
+{
+    /** @param list<Error> $errors */
+    public function __construct(
+        public readonly array $errors = [],
+    ) {
+    }
+}
diff --git a/src/Subscription/Engine/SubscriptionEngine.php b/src/Subscription/Engine/SubscriptionEngine.php
index 0e4229eaa..bdba70f12 100644
--- a/src/Subscription/Engine/SubscriptionEngine.php
+++ b/src/Subscription/Engine/SubscriptionEngine.php
@@ -8,7 +8,7 @@
 
 interface SubscriptionEngine
 {
-    public function setup(SubscriptionEngineCriteria|null $criteria = null, bool $skipBooting = false): void;
+    public function setup(SubscriptionEngineCriteria|null $criteria = null, bool $skipBooting = false): Result;
 
     /**
      * @param positive-int|null $limit
@@ -18,7 +18,7 @@ public function setup(SubscriptionEngineCriteria|null $criteria = null, bool $sk
     public function boot(
         SubscriptionEngineCriteria|null $criteria = null,
         int|null $limit = null,
-    ): void;
+    ): ProcessedResult;
 
     /**
      * @param positive-int|null $limit
@@ -28,15 +28,15 @@ public function boot(
     public function run(
         SubscriptionEngineCriteria|null $criteria = null,
         int|null $limit = null,
-    ): void;
+    ): ProcessedResult;
 
-    public function teardown(SubscriptionEngineCriteria|null $criteria = null): void;
+    public function teardown(SubscriptionEngineCriteria|null $criteria = null): Result;
 
-    public function remove(SubscriptionEngineCriteria|null $criteria = null): void;
+    public function remove(SubscriptionEngineCriteria|null $criteria = null): Result;
 
-    public function reactivate(SubscriptionEngineCriteria|null $criteria = null): void;
+    public function reactivate(SubscriptionEngineCriteria|null $criteria = null): Result;
 
-    public function pause(SubscriptionEngineCriteria|null $criteria = null): void;
+    public function pause(SubscriptionEngineCriteria|null $criteria = null): Result;
 
     /** @return list<Subscription> */
     public function subscriptions(SubscriptionEngineCriteria|null $criteria = null): array;
diff --git a/src/Subscription/Store/DoctrineSubscriptionStore.php b/src/Subscription/Store/DoctrineSubscriptionStore.php
index 63a6d5c44..661d833d9 100644
--- a/src/Subscription/Store/DoctrineSubscriptionStore.php
+++ b/src/Subscription/Store/DoctrineSubscriptionStore.php
@@ -182,12 +182,21 @@ public function remove(Subscription $subscription): void
         $this->connection->delete($this->tableName, ['id' => $subscription->id()]);
     }
 
-    public function inLock(Closure $closure): void
+    /**
+     * @param Closure():T $closure
+     *
+     * @return T
+     *
+     * @throws TransactionCommitNotPossible
+     *
+     * @template T
+     */
+    public function inLock(Closure $closure): mixed
     {
         $this->connection->beginTransaction();
 
         try {
-            $closure();
+            return $closure();
         } finally {
             try {
                 $this->connection->commit();
diff --git a/src/Subscription/Store/LockableSubscriptionStore.php b/src/Subscription/Store/LockableSubscriptionStore.php
index 48d62366e..2163aa6a7 100644
--- a/src/Subscription/Store/LockableSubscriptionStore.php
+++ b/src/Subscription/Store/LockableSubscriptionStore.php
@@ -8,5 +8,14 @@
 
 interface LockableSubscriptionStore extends SubscriptionStore
 {
-    public function inLock(Closure $closure): void;
+    /**
+     * @param Closure():T $closure
+     *
+     * @return T
+     *
+     * @throws TransactionCommitNotPossible
+     *
+     * @template T
+     */
+    public function inLock(Closure $closure): mixed;
 }
diff --git a/tests/Integration/Subscription/SubscriptionTest.php b/tests/Integration/Subscription/SubscriptionTest.php
index 603dd9bce..290bb8761 100644
--- a/tests/Integration/Subscription/SubscriptionTest.php
+++ b/tests/Integration/Subscription/SubscriptionTest.php
@@ -105,8 +105,14 @@ public function testHappyPath(): void
             $engine->subscriptions(),
         );
 
-        $engine->setup();
-        $engine->boot();
+        $result = $engine->setup();
+
+        self::assertEquals([], $result->errors);
+
+        $result = $engine->boot();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals(
             [
@@ -124,7 +130,10 @@ public function testHappyPath(): void
         $profile = Profile::create(ProfileId::fromString('1'), 'John');
         $repository->save($profile);
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals(
             [
@@ -150,7 +159,8 @@ public function testHappyPath(): void
         self::assertSame('1', $result['id']);
         self::assertSame('John', $result['name']);
 
-        $engine->remove();
+        $result = $engine->remove();
+        self::assertEquals([], $result->errors);
 
         self::assertEquals(
             [
@@ -213,8 +223,12 @@ public function testErrorHandling(): void
             ),
         );
 
-        $engine->setup();
-        $engine->boot();
+        $result = $engine->setup();
+        self::assertEquals([], $result->errors);
+
+        $result = $engine->boot();
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
@@ -228,7 +242,16 @@ public function testErrorHandling(): void
         $repository->save($profile);
 
         $subscriber->subscribeError = true;
-        $engine->run();
+
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals('error_producer', $error->subscriptionId);
+        self::assertEquals('subscribe error', $error->message);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
@@ -237,7 +260,10 @@ public function testErrorHandling(): void
         self::assertEquals(Status::Active, $subscription->subscriptionError()?->previousStatus);
         self::assertEquals(0, $subscription->retryAttempt());
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
@@ -248,7 +274,15 @@ public function testErrorHandling(): void
 
         $clock->sleep(5);
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals('error_producer', $error->subscriptionId);
+        self::assertEquals('subscribe error', $error->message);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
@@ -259,7 +293,15 @@ public function testErrorHandling(): void
 
         $clock->sleep(10);
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals('error_producer', $error->subscriptionId);
+        self::assertEquals('subscribe error', $error->message);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
@@ -278,7 +320,15 @@ public function testErrorHandling(): void
         self::assertEquals(null, $subscription->subscriptionError());
         self::assertEquals(0, $subscription->retryAttempt());
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals('error_producer', $error->subscriptionId);
+        self::assertEquals('subscribe error', $error->message);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
@@ -290,7 +340,10 @@ public function testErrorHandling(): void
         $clock->sleep(5);
         $subscriber->subscribeError = false;
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         $subscription = self::findSubscription($engine->subscriptions(), 'error_producer');
 
diff --git a/tests/Unit/Subscription/Engine/DefaultSubscriptionEngineTest.php b/tests/Unit/Subscription/Engine/DefaultSubscriptionEngineTest.php
index e6ce5068c..3742081df 100644
--- a/tests/Unit/Subscription/Engine/DefaultSubscriptionEngineTest.php
+++ b/tests/Unit/Subscription/Engine/DefaultSubscriptionEngineTest.php
@@ -55,10 +55,11 @@ public function testNothingToSetup(): void
             logger: new NullLogger(),
         );
 
-        $engine->setup();
+        $result = $engine->setup();
 
         self::assertEquals([], $store->addedSubscriptions);
         self::assertEquals([], $store->updatedSubscriptions);
+        self::assertEquals([], $result->errors);
     }
 
     public function testSetupWithoutCreateMethod(): void
@@ -82,7 +83,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->setup();
+        $result = $engine->setup();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -131,7 +134,9 @@ public function create(): void
             logger: new NullLogger(),
         );
 
-        $engine->setup();
+        $result = $engine->setup();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -187,7 +192,15 @@ public function create(): void
             logger: new NullLogger(),
         );
 
-        $engine->setup();
+        $result = $engine->setup();
+
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals($subscriptionId, $error->subscriptionId);
+        self::assertEquals('ERROR', $error->message);
+        self::assertInstanceOf(RuntimeException::class, $error->throwable);
 
         self::assertEquals(
             [
@@ -236,7 +249,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->setup(null, true);
+        $result = $engine->setup(null, true);
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -276,7 +291,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->setup();
+        $result = $engine->setup();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -315,7 +332,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->setup();
+        $result = $engine->setup();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -342,7 +361,10 @@ public function testNothingToBoot(): void
             logger: new NullLogger(),
         );
 
-        $engine->boot();
+        $result = $engine->boot();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $store->addedSubscriptions);
         self::assertEquals([], $store->updatedSubscriptions);
@@ -367,7 +389,10 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->boot();
+        $result = $engine->boot();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -416,7 +441,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->boot();
+        $result = $engine->boot();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->addedSubscriptions);
 
@@ -440,6 +468,74 @@ public function handle(Message $message): void
         self::assertSame($message, $subscriber->message);
     }
 
+    public function testBootWithError(): void
+    {
+        $subscriptionId = 'test';
+        $subscriber = new #[Subscriber('test', RunMode::FromBeginning)]
+        class {
+            public function __construct(
+                public readonly RuntimeException $exception = new RuntimeException('ERROR'),
+            ) {
+            }
+
+            #[Subscribe(ProfileVisited::class)]
+            public function handle(Message $message): void
+            {
+                throw $this->exception;
+            }
+        };
+
+        $subscriptionStore = new DummySubscriptionStore([
+            new Subscription(
+                $subscriptionId,
+                Subscription::DEFAULT_GROUP,
+                RunMode::FromBeginning,
+                Status::Booting,
+            ),
+        ]);
+
+        $message = new Message(new ProfileVisited(ProfileId::fromString('test')));
+
+        $streamableStore = $this->prophesize(Store::class);
+        $streamableStore->load($this->criteria())->willReturn(new ArrayStream([$message]))->shouldBeCalledOnce();
+
+        $engine = new DefaultSubscriptionEngine(
+            $streamableStore->reveal(),
+            $subscriptionStore,
+            new MetadataSubscriberAccessorRepository([$subscriber]),
+            logger: new NullLogger(),
+        );
+
+        $result = $engine->boot();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals($subscriptionId, $error->subscriptionId);
+        self::assertEquals('ERROR', $error->message);
+        self::assertInstanceOf(RuntimeException::class, $error->throwable);
+
+        self::assertEquals(
+            [
+                new Subscription(
+                    $subscriptionId,
+                    Subscription::DEFAULT_GROUP,
+                    RunMode::FromBeginning,
+                    Status::Error,
+                    0,
+                    new SubscriptionError(
+                        'ERROR',
+                        Status::Booting,
+                        ThrowableToErrorContextTransformer::transform($subscriber->exception),
+                    ),
+                ),
+            ],
+            $subscriptionStore->updatedSubscriptions,
+        );
+    }
+
     public function testBootWithLimit(): void
     {
         $subscriptionId = 'test';
@@ -475,7 +571,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->boot(new SubscriptionEngineCriteria(), 1);
+        $result = $engine->boot(new SubscriptionEngineCriteria(), 1);
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->addedSubscriptions);
 
@@ -546,7 +645,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->boot();
+        $result = $engine->boot();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -620,7 +722,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->boot();
+        $result = $engine->boot();
+
+        self::assertEquals(2, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -677,7 +782,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->boot();
+        $result = $engine->boot();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -716,7 +824,10 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -763,7 +874,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -817,7 +931,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->run(new SubscriptionEngineCriteria(), 1);
+        $result = $engine->run(new SubscriptionEngineCriteria(), 1);
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -886,7 +1003,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -947,7 +1067,16 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals($subscriptionId, $error->subscriptionId);
+        self::assertEquals('ERROR', $error->message);
+        self::assertInstanceOf(RuntimeException::class, $error->throwable);
 
         self::assertEquals(
             [
@@ -968,7 +1097,7 @@ public function handle(Message $message): void
         );
     }
 
-    public function testRunningMarkOutdated(): void
+    public function testRunningMarkDetached(): void
     {
         $subscriptionId = 'test';
 
@@ -991,7 +1120,10 @@ public function testRunningMarkOutdated(): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1027,7 +1159,10 @@ public function testRunningWithoutActiveSubscribers(): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
     }
@@ -1069,7 +1204,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(2, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1119,7 +1257,10 @@ public function handle(Message $message): void
             logger: new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1158,7 +1299,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->teardown();
+        $result = $engine->teardown();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1195,7 +1338,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->teardown();
+        $result = $engine->teardown();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([$subscription], $subscriptionStore->removedSubscriptions);
@@ -1234,7 +1379,9 @@ public function drop(): void
             logger: new NullLogger(),
         );
 
-        $engine->teardown();
+        $result = $engine->teardown();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([$subscription], $subscriptionStore->removedSubscriptions);
@@ -1274,7 +1421,15 @@ public function drop(): void
             logger: new NullLogger(),
         );
 
-        $engine->teardown();
+        $result = $engine->teardown();
+
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals($subscriptionId, $error->subscriptionId);
+        self::assertEquals('ERROR', $error->message);
+        self::assertInstanceOf(RuntimeException::class, $error->throwable);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([], $subscriptionStore->removedSubscriptions);
@@ -1302,7 +1457,9 @@ public function testTeardownWithoutSubscriber(): void
             logger: new NullLogger(),
         );
 
-        $engine->teardown();
+        $result = $engine->teardown();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([], $subscriptionStore->removedSubscriptions);
@@ -1325,7 +1482,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->remove();
+        $result = $engine->remove();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1368,7 +1527,9 @@ public function drop(): void
             logger: new NullLogger(),
         );
 
-        $engine->remove();
+        $result = $engine->remove();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([$subscription], $subscriptionStore->removedSubscriptions);
@@ -1399,7 +1560,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->remove();
+        $result = $engine->remove();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([$subscription], $subscriptionStore->removedSubscriptions);
@@ -1436,7 +1599,15 @@ public function drop(): void
             logger: new NullLogger(),
         );
 
-        $engine->remove();
+        $result = $engine->remove();
+
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals($subscriptionId, $error->subscriptionId);
+        self::assertEquals('ERROR', $error->message);
+        self::assertInstanceOf(RuntimeException::class, $error->throwable);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([$subscription], $subscriptionStore->removedSubscriptions);
@@ -1463,7 +1634,9 @@ public function testRemoveWithoutSubscriber(): void
             logger: new NullLogger(),
         );
 
-        $engine->remove();
+        $result = $engine->remove();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
         self::assertEquals([$subscription], $subscriptionStore->removedSubscriptions);
@@ -1486,7 +1659,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->reactivate();
+        $result = $engine->reactivate();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1525,7 +1700,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->reactivate();
+        $result = $engine->reactivate();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1538,7 +1715,7 @@ class {
         ], $subscriptionStore->updatedSubscriptions);
     }
 
-    public function testReactivateOutdated(): void
+    public function testReactivateDetached(): void
     {
         $subscriptionId = 'test';
         $subscriber = new #[Subscriber('test', RunMode::FromBeginning)]
@@ -1563,7 +1740,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->reactivate();
+        $result = $engine->reactivate();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1600,7 +1779,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->reactivate();
+        $result = $engine->reactivate();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1637,7 +1818,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->reactivate();
+        $result = $engine->reactivate();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1666,7 +1849,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->pause();
+        $result = $engine->pause();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1703,7 +1888,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->pause();
+        $result = $engine->pause();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1740,7 +1927,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->pause();
+        $result = $engine->pause();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1779,7 +1968,9 @@ class {
             logger: new NullLogger(),
         );
 
-        $engine->pause();
+        $result = $engine->pause();
+
+        self::assertEquals([], $result->errors);
 
         self::assertEquals([
             new Subscription(
@@ -1870,7 +2061,16 @@ public function subscribe(): void
             new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(1, $result->processedMessages);
+        self::assertCount(1, $result->errors);
+
+        $error = $result->errors[0];
+
+        self::assertEquals($subscriptionId, $error->subscriptionId);
+        self::assertEquals('ERROR2', $error->message);
+        self::assertInstanceOf(RuntimeException::class, $error->throwable);
 
         self::assertCount(2, $subscriptionStore->updatedSubscriptions);
 
@@ -1923,7 +2123,10 @@ class {
             new NullLogger(),
         );
 
-        $engine->run();
+        $result = $engine->run();
+
+        self::assertEquals(0, $result->processedMessages);
+        self::assertCount(0, $result->errors);
 
         self::assertEquals([], $subscriptionStore->updatedSubscriptions);
     }