diff --git a/lib/Exceptions/CoordinatedOperationCleanupFailedException.php b/lib/Exceptions/CoordinatedOperationCleanupFailedException.php
new file mode 100644
index 0000000..2566897
--- /dev/null
+++ b/lib/Exceptions/CoordinatedOperationCleanupFailedException.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace PHPNomad\Database\Exceptions;
+
+use Throwable;
+
+/** An operation failed and its cleanup could not establish a safe outcome. */
+class CoordinatedOperationCleanupFailedException extends CoordinatedOperationOutcomeUnknownException
+{
+    private Throwable $operationFailure;
+
+    /** Retain the cleanup failure as previous and the earlier operation failure separately. */
+    public function __construct(Throwable $operationFailure, Throwable $cleanupFailure)
+    {
+        $this->operationFailure = $operationFailure;
+
+        parent::__construct(
+            'The coordinated operation failed and cleanup could not be confirmed.',
+            0,
+            $cleanupFailure
+        );
+    }
+
+    /** Return the exact earlier failure that required cleanup. */
+    public function getOperationFailure(): Throwable
+    {
+        return $this->operationFailure;
+    }
+}
diff --git a/tests/Unit/Contracts/CoordinationCleanupFailureContractTest.php b/tests/Unit/Contracts/CoordinationCleanupFailureContractTest.php
new file mode 100644
index 0000000..6d78d02
--- /dev/null
+++ b/tests/Unit/Contracts/CoordinationCleanupFailureContractTest.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace PHPNomad\Database\Tests\Unit\Contracts;
+
+use Error;
+use PHPNomad\Database\Exceptions\CoordinatedOperationCleanupFailedException;
+use PHPNomad\Database\Exceptions\CoordinatedOperationConflictException;
+use PHPNomad\Database\Exceptions\CoordinatedOperationOutcomeUnknownException;
+use PHPNomad\Datastore\Exceptions\DatastoreErrorException;
+use PHPNomad\Database\Tests\TestCase;
+use RuntimeException;
+
+/** Keeps both causes without depending on a storage adapter. Each adapter tests its cleanup behavior. */
+final class CoordinationCleanupFailureContractTest extends TestCase
+{
+    /** @dataProvider causeKinds */
+    public function testBothOriginalFailuresRemainInspectableAsAnUnknownOutcome(bool $operationIsError, bool $cleanupIsError): void
+    {
+        $operation = $operationIsError ? new Error('Private operation detail') : new RuntimeException('Private operation detail');
+        $cleanup = $cleanupIsError ? new Error('Private cleanup detail') : new RuntimeException('Private cleanup detail');
+        $failure = new CoordinatedOperationCleanupFailedException($operation, $cleanup);
+
+        self::assertInstanceOf(CoordinatedOperationOutcomeUnknownException::class, $failure);
+        self::assertInstanceOf(DatastoreErrorException::class, $failure);
+        self::assertNotInstanceOf(CoordinatedOperationConflictException::class, $failure);
+        self::assertSame($operation, $failure->getOperationFailure());
+        self::assertSame($cleanup, $failure->getPrevious());
+        self::assertSame('The coordinated operation failed and cleanup could not be confirmed.', $failure->getMessage());
+        self::assertSame(0, $failure->getCode());
+        self::assertNull($operation->getPrevious());
+        self::assertNull($cleanup->getPrevious());
+
+        $otherOperation = new RuntimeException('Another operation');
+        $otherCleanup = new RuntimeException('Another cleanup');
+        $other = new CoordinatedOperationCleanupFailedException($otherOperation, $otherCleanup);
+        self::assertSame($otherOperation, $other->getOperationFailure());
+        self::assertSame($otherCleanup, $other->getPrevious());
+        self::assertSame($operation, $failure->getOperationFailure());
+        self::assertSame($cleanup, $failure->getPrevious());
+    }
+
+    /** @return array<string, array{bool, bool}> */
+    public static function causeKinds(): array
+    {
+        return [
+            'exceptions' => [false, false], 'operation error' => [true, false],
+            'cleanup error' => [false, true], 'both errors' => [true, true],
+        ];
+    }
+}