diff --git a/Classes/Core/Functional/FunctionalTestCase.php b/Classes/Core/Functional/FunctionalTestCase.php
index 7e71dfd7..58edd8e2 100644
--- a/Classes/Core/Functional/FunctionalTestCase.php
+++ b/Classes/Core/Functional/FunctionalTestCase.php
@@ -295,7 +295,9 @@ protected function setUp(): void
                 'extbase',
                 'fluid',
             ];
-            if ((new Typo3Version())->getMajorVersion() < 13) {
+            if ((new Typo3Version())->getMajorVersion() < 13
+                && class_exists(\TYPO3\CMS\Install\Exception::class)
+            ) {
                 // @todo: Remove with next major TF version
                 $defaultCoreExtensionsToLoad[] = 'install';
             }
diff --git a/Classes/Core/Testbase.php b/Classes/Core/Testbase.php
index d3d4bb0d..9b04635d 100644
--- a/Classes/Core/Testbase.php
+++ b/Classes/Core/Testbase.php
@@ -236,19 +236,22 @@ public function setUpInstanceCoreLinks(
         // of the testing framework.
         // @todo: Remove else branch when dropping support for v12
         $hasConsolidatedHttpEntryPoint = class_exists(CoreHttpApplication::class);
+        $installPhpExists = file_exists($instancePath . '/typo3/sysext/install/Resources/Private/Php/install.php');
         if ($hasConsolidatedHttpEntryPoint) {
             $entryPointsToSet = [
                 $instancePath . '/typo3/sysext/core/Resources/Private/Php/index.php' => $instancePath . '/index.php',
             ];
-            if (in_array('install', $coreExtensions, true)) {
+            if ($installPhpExists && in_array('install', $coreExtensions, true)) {
                 $entryPointsToSet[$instancePath . '/typo3/sysext/install/Resources/Private/Php/install.php'] = $instancePath . '/typo3/install.php';
             }
         } else {
             $entryPointsToSet = [
                 $instancePath . '/typo3/sysext/backend/Resources/Private/Php/backend.php' => $instancePath . '/typo3/index.php',
                 $instancePath . '/typo3/sysext/frontend/Resources/Private/Php/frontend.php' => $instancePath . '/index.php',
-                $instancePath . '/typo3/sysext/install/Resources/Private/Php/install.php' => $instancePath . '/typo3/install.php',
             ];
+            if ($installPhpExists) {
+                $entryPointsToSet[$instancePath . '/typo3/sysext/install/Resources/Private/Php/install.php'] = $instancePath . '/typo3/install.php';
+            }
         }
         $autoloadFile = dirname(__DIR__, 4) . '/autoload.php';