diff --git a/src/SessionManager.php b/src/SessionManager.php
index 3bb41b3c..2f969a3d 100644
--- a/src/SessionManager.php
+++ b/src/SessionManager.php
@@ -9,6 +9,8 @@
 
 use function array_key_exists;
 use function array_merge;
+use function constant;
+use function defined;
 use function headers_sent;
 use function is_array;
 use function iterator_to_array;
@@ -91,12 +93,19 @@ public function sessionExists()
             return true;
         }
 
-        if ($this->getId()) {
+        /**
+         * @var string|false $sid
+         */
+        $sid = defined('SID') ? constant('SID') : false;
+
+        if ($sid !== false && $this->getId()) {
             return true;
         }
+
         if (headers_sent()) {
             return true;
         }
+
         return false;
     }
 
diff --git a/test/SessionManagerTest.php b/test/SessionManagerTest.php
index 301f7034..ceb684cf 100644
--- a/test/SessionManagerTest.php
+++ b/test/SessionManagerTest.php
@@ -17,6 +17,8 @@
 use Laminas\Session\Validator\Id;
 use Laminas\Session\Validator\RemoteAddr;
 use LaminasTest\Session\TestAsset\Php81CompatibleStorageInterface;
+use PHPUnit\Framework\Attributes\IgnoreDeprecations;
+use PHPUnit\Framework\Attributes\RunInSeparateProcess;
 use PHPUnit\Framework\TestCase;
 use Traversable;
 
@@ -35,6 +37,7 @@
 use function session_write_close;
 use function set_error_handler;
 use function stristr;
+use function uniqid;
 use function var_export;
 use function xdebug_get_headers;
 
@@ -157,20 +160,14 @@ public function testCanDisableAttachDefaultValidators(): void
         $this->assertAttributeEquals([], 'validators', $manager);
     }
 
-    // Session-related functionality
-
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSessionExistsReturnsFalseWhenNoSessionStarted(): void
     {
         $this->manager = new SessionManager();
         self::assertFalse($this->manager->sessionExists());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSessionExistsReturnsTrueWhenSessionStarted(): void
     {
         $this->manager = new SessionManager();
@@ -178,9 +175,8 @@ public function testSessionExistsReturnsTrueWhenSessionStarted(): void
         self::assertTrue($this->manager->sessionExists());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
     public function testSessionExistsReturnsTrueWhenSessionStartedThenWritten(): void
     {
         $this->manager = new SessionManager();
@@ -189,9 +185,8 @@ public function testSessionExistsReturnsTrueWhenSessionStartedThenWritten(): voi
         self::assertTrue($this->manager->sessionExists());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
     public function testSessionExistsReturnsFalseWhenSessionStartedThenDestroyed(): void
     {
         $this->manager = new SessionManager();
@@ -200,9 +195,7 @@ public function testSessionExistsReturnsFalseWhenSessionStartedThenDestroyed():
         self::assertFalse($this->manager->sessionExists());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSessionIsStartedAfterCallingStart(): void
     {
         $this->manager = new SessionManager();
@@ -211,9 +204,8 @@ public function testSessionIsStartedAfterCallingStart(): void
         self::assertTrue($this->manager->sessionExists());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
     public function testStartDoesNothingWhenCalledAfterWriteCloseOperation(): void
     {
         $this->manager = new SessionManager();
@@ -226,9 +218,7 @@ public function testStartDoesNothingWhenCalledAfterWriteCloseOperation(): void
         self::assertEquals($id1, $id2);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testStartWithOldTraversableSessionData(): void
     {
         // pre-populate session with data
@@ -245,9 +235,7 @@ public function testStartWithOldTraversableSessionData(): void
         self::assertEquals('value2', $_SESSION->key2);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testStorageContentIsPreservedByWriteCloseOperation(): void
     {
         $this->manager = new SessionManager();
@@ -259,9 +247,8 @@ public function testStorageContentIsPreservedByWriteCloseOperation(): void
         self::assertEquals('bar', $storage['foo']);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
     public function testStartCreatesNewSessionIfPreviousSessionHasBeenDestroyed(): void
     {
         $this->manager = new SessionManager();
@@ -274,9 +261,7 @@ public function testStartCreatesNewSessionIfPreviousSessionHasBeenDestroyed(): v
         self::assertNotEquals($id1, $id2);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testStartConvertsSessionDataFromStorageInterfaceToArrayBeforeMerging(): void
     {
         $this->manager = new SessionManager();
@@ -298,9 +283,7 @@ public function testStartConvertsSessionDataFromStorageInterfaceToArrayBeforeMer
         self::assertSame($data[$key], $_SESSION[$key]);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testStartConvertsSessionDataFromTraversableToArrayBeforeMerging(): void
     {
         $this->manager = new SessionManager();
@@ -334,9 +317,7 @@ public function testStartWillNotBlockHeaderSentNotices(): void
         self::assertContains('already sent', $this->error);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testGetNameReturnsSessionName(): void
     {
         $this->manager = new SessionManager();
@@ -344,9 +325,7 @@ public function testGetNameReturnsSessionName(): void
         self::assertEquals($ini, $this->manager->getName());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSetNameRaisesExceptionOnInvalidName(): void
     {
         $this->manager = new SessionManager();
@@ -355,9 +334,7 @@ public function testSetNameRaisesExceptionOnInvalidName(): void
         $this->manager->setName('foo bar!');
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSetNameSetsSessionNameOnSuccess(): void
     {
         $this->manager = new SessionManager();
@@ -366,9 +343,8 @@ public function testSetNameSetsSessionNameOnSuccess(): void
         self::assertEquals('foobar', session_name());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
     public function testCanSetNewSessionNameAfterSessionDestroyed(): void
     {
         $this->manager = new SessionManager();
@@ -379,9 +355,7 @@ public function testCanSetNewSessionNameAfterSessionDestroyed(): void
         self::assertEquals('foobar', session_name());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSettingNameWhenAnActiveSessionExistsRaisesException(): void
     {
         $this->manager = new SessionManager();
@@ -391,9 +365,7 @@ public function testSettingNameWhenAnActiveSessionExistsRaisesException(): void
         $this->manager->setName('foobar');
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testDestroyByDefaultSendsAnExpireCookie(): void
     {
         if (! extension_loaded('xdebug')) {
@@ -424,9 +396,7 @@ public function testDestroyByDefaultSendsAnExpireCookie(): void
         self::assertTrue($found, 'No session cookie found: ' . var_export($headers, true));
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSendingFalseToSendExpireCookieWhenCallingDestroyShouldNotSendCookie(): void
     {
         if (! extension_loaded('xdebug')) {
@@ -461,9 +431,7 @@ public function testSendingFalseToSendExpireCookieWhenCallingDestroyShouldNotSen
         }
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testDestroyDoesNotClearSessionStorageByDefault(): void
     {
         $this->manager = new SessionManager();
@@ -475,9 +443,7 @@ public function testDestroyDoesNotClearSessionStorageByDefault(): void
         self::assertEquals('bar', $storage['foo']);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testPassingClearStorageOptionWhenCallingDestroyClearsStorage(): void
     {
         $this->manager = new SessionManager();
@@ -488,9 +454,7 @@ public function testPassingClearStorageOptionWhenCallingDestroyClearsStorage():
         self::assertFalse(isset($storage['foo']));
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testDestroySessionWhenHeadersHaveBeenSent(): void
     {
         $this->manager = new SessionManager();
@@ -503,9 +467,7 @@ public function testDestroySessionWhenHeadersHaveBeenSent(): void
         self::assertFalse(isset($storage['foo']));
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testCallingWriteCloseMarksStorageAsImmutable(): void
     {
         $this->manager = new SessionManager();
@@ -516,9 +478,8 @@ public function testCallingWriteCloseMarksStorageAsImmutable(): void
         self::assertTrue($storage->isImmutable());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
     public function testCallingWriteCloseShouldNotAlterSessionExistsStatus(): void
     {
         $this->manager = new SessionManager();
@@ -527,18 +488,14 @@ public function testCallingWriteCloseShouldNotAlterSessionExistsStatus(): void
         self::assertTrue($this->manager->sessionExists());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testIdShouldBeEmptyPriorToCallingStart(): void
     {
         $this->manager = new SessionManager();
         self::assertSame('', $this->manager->getId());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testIdShouldBeMutablePriorToCallingStart(): void
     {
         $this->manager = new SessionManager();
@@ -547,9 +504,7 @@ public function testIdShouldBeMutablePriorToCallingStart(): void
         self::assertSame(self::class, session_id());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testIdShouldNotBeMutableAfterSessionStarted(): void
     {
         $this->manager = new SessionManager();
@@ -561,9 +516,7 @@ public function testIdShouldNotBeMutableAfterSessionStarted(): void
         $this->manager->setId(__METHOD__);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRegenerateIdShouldWorkAfterSessionStarted(): void
     {
         $this->manager = new SessionManager();
@@ -573,9 +526,7 @@ public function testRegenerateIdShouldWorkAfterSessionStarted(): void
         self::assertNotSame($origId, $this->manager->getId());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRegenerateIdDoesNothingWhenSessioIsNotStarted(): void
     {
         $this->manager = new SessionManager();
@@ -585,9 +536,7 @@ public function testRegenerateIdDoesNothingWhenSessioIsNotStarted(): void
         self::assertEquals('', $this->manager->getId());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRegeneratingIdAfterSessionStartedShouldSendExpireCookie(): void
     {
         if (! extension_loaded('xdebug')) {
@@ -617,9 +566,7 @@ public function testRegeneratingIdAfterSessionStartedShouldSendExpireCookie(): v
         self::assertTrue($found, 'No session cookie found: ' . var_export($headers, true));
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRememberMeShouldSendNewSessionCookieWithUpdatedTimestamp(): void
     {
         if (! extension_loaded('xdebug')) {
@@ -663,9 +610,7 @@ public function testRememberMeShouldSendNewSessionCookieWithUpdatedTimestamp():
         );
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRememberMeShouldSetTimestampBasedOnConfigurationByDefault(): void
     {
         if (! extension_loaded('xdebug')) {
@@ -715,9 +660,7 @@ public function testRememberMeShouldSetTimestampBasedOnConfigurationByDefault():
         );
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testForgetMeShouldSendCookieWithZeroTimestamp(): void
     {
         if (! extension_loaded('xdebug')) {
@@ -748,9 +691,7 @@ public function testForgetMeShouldSendCookieWithZeroTimestamp(): void
         self::assertStringNotContainsString('expires=', $header);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testStartingSessionThatFailsAValidatorShouldRaiseException(): void
     {
         $this->manager = new SessionManager();
@@ -761,9 +702,7 @@ public function testStartingSessionThatFailsAValidatorShouldRaiseException(): vo
         $this->manager->start();
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testResumeSessionThatFailsAValidatorShouldRaiseException(): void
     {
         $this->manager = new SessionManager();
@@ -773,9 +712,7 @@ public function testResumeSessionThatFailsAValidatorShouldRaiseException(): void
         $this->manager->start();
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSessionWriteCloseStoresMetadata(): void
     {
         $this->manager = new SessionManager();
@@ -787,9 +724,7 @@ public function testSessionWriteCloseStoresMetadata(): void
         self::assertSame($_SESSION['__Laminas'], $metaData);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testSessionValidationDoesNotHaltOnNoopListener(): void
     {
         $this->manager   = new SessionManager();
@@ -804,9 +739,7 @@ public function testSessionValidationDoesNotHaltOnNoopListener(): void
         self::assertTrue($validatorCalled);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testProducedSessionManagerWillNotReplaceSessionSuperGlobalValues(): void
     {
         $this->manager   = new SessionManager();
@@ -818,9 +751,7 @@ public function testProducedSessionManagerWillNotReplaceSessionSuperGlobalValues
         self::assertSame('bar', $_SESSION['foo']);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testValidatorChainSessionMetadataIsPreserved(): void
     {
         $this->manager = new SessionManager();
@@ -836,9 +767,7 @@ public function testValidatorChainSessionMetadataIsPreserved(): void
         self::assertEquals('', $_SESSION['__Laminas']['_VALID'][RemoteAddr::class]);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRemoteAddressValidationWillFailOnInvalidAddress(): void
     {
         $this->manager = new SessionManager();
@@ -850,9 +779,7 @@ public function testRemoteAddressValidationWillFailOnInvalidAddress(): void
         $this->manager->start();
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRemoteAddressValidationWillSucceedWithValidPreSetData(): void
     {
         $this->manager = new SessionManager();
@@ -869,9 +796,7 @@ public function testRemoteAddressValidationWillSucceedWithValidPreSetData(): voi
         self::assertTrue($this->manager->isValid());
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testRemoteAddressValidationWillFailWithInvalidPreSetData(): void
     {
         $this->manager = new SessionManager();
@@ -888,9 +813,7 @@ public function testRemoteAddressValidationWillFailWithInvalidPreSetData(): void
         $this->manager->start();
     }
 
-    /**
-     * @runInSeparateProcess
-     */
+    #[RunInSeparateProcess]
     public function testIdValidationWillFailOnInvalidData(): void
     {
         $this->manager = new SessionManager();
@@ -902,6 +825,30 @@ public function testIdValidationWillFailOnInvalidData(): void
         $this->manager->start();
     }
 
+    #[RunInSeparateProcess]
+    #[IgnoreDeprecations]
+    public function testSettingTheIdentifierBeforeStartingTheSessionYieldsTheExpectedId(): void
+    {
+        $manager = new SessionManager();
+
+        $id = uniqid();
+
+        $manager->setId($id);
+
+        // setting a session id does not mark a session as started
+        self::assertFalse($manager->sessionExists());
+
+        $manager->start();
+
+        self::assertTrue($manager->sessionExists());
+
+        $manager->writeClose();
+
+        // calling writeClose() does not mark the session as closed
+        self::assertTrue($manager->sessionExists());
+        self::assertSame($id, $manager->getId());
+    }
+
     /** @param non-empty-string $property */
     private function assertAttributeEquals(mixed $expected, string $property, object $object): void
     {