Error: Call to undefined method Drupal\Core\File\FileSystem::scanDirectory()

I have a project and this morning I ran a composer update on it and after that, my bootstrap updated to the new version 3.22 and I get this error:

Error: Call to undefined method Drupal\Core\File\FileSystem::scanDirectory() in Drupal\bootstrap\Theme->fileScan() (line 355 of /Users/john/Sites/devdesktop/project/vkp/docroot/themes/contrib/bootstrap/src/Theme.php) #0 /Users/john/Sites/devdesktop/project/vkp/docroot/themes/contrib/bootstrap/src/Plugin/Alter/ThemeRegistry.php(82): Drupal\bootstrap\Theme->fileScan('/\\.html\\.twig$/') #1 /Users/john/Sites/devdesktop/project/vkp/docroot/themes/contrib/bootstrap/src/Bootstrap.php(303): Drupal\bootstrap\Plugin\Alter\ThemeRegistry->alter(Array, NULL, NULL) #2 /Users/john/Sites/devdesktop/project/vkp/docroot/themes/contrib/bootstrap/bootstrap.theme(139): Drupal\bootstrap\Bootstrap::alter('bootstrap_theme...', Array, NULL, NULL) #3 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Theme/ThemeManager.php(449): bootstrap_theme_registry_alter(Array, NULL, NULL) #4 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Theme/Registry.php(367): Drupal\Core\Theme\ThemeManager->alterForTheme(Object(Drupal\Core\Theme\ActiveTheme), 'theme_registry', Array) #5 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Theme/Registry.php(233): Drupal\Core\Theme\Registry->build() #6 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Utility/ThemeRegistry.php(86): Drupal\Core\Theme\Registry->get() #7 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Utility/ThemeRegistry.php(67): Drupal\Core\Utility\ThemeRegistry->initializeRegistry() #8 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Theme/Registry.php(253): Drupal\Core\Utility\ThemeRegistry->__construct('theme_registry:...', Object(Drupal\Core\Cache\DatabaseBackend), Object(Drupal\Core\ProxyClass\Lock\DatabaseLockBackend), Array, true) #9 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Theme/ThemeManager.php(142): Drupal\Core\Theme\Registry->getRuntime() #10 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/Renderer.php(437): Drupal\Core\Theme\ThemeManager->render(Array, Array) #11 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/Renderer.php(450): Drupal\Core\Render\Renderer->doRender(Array) #12 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/Renderer.php(195): Drupal\Core\Render\Renderer->doRender(Array, false) #13 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(226): Drupal\Core\Render\Renderer->render(Array, false) #14 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/Renderer.php(582): Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() #15 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(227): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure)) #16 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(117): Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\CurrentRouteMatch)) #17 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php(90): Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\CurrentRouteMatch)) #18 [internal function]: Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent), 'kernel.view', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher)) #19 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(111): call_user_func(Array, Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent), 'kernel.view', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher)) #20 /Users/john/Sites/devdesktop/project/vkp/vendor/symfony/http-kernel/HttpKernel.php(156): Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view', Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent)) #21 /Users/john/Sites/devdesktop/project/vkp/vendor/symfony/http-kernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1) #22 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/StackMiddleware/Session.php(57): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #23 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #24 /Users/john/Sites/devdesktop/project/vkp/docroot/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #25 /Users/john/Sites/devdesktop/project/vkp/docroot/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true) #26 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #27 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(52): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #28 /Users/john/Sites/devdesktop/project/vkp/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #29 /Users/john/Sites/devdesktop/project/vkp/docroot/core/lib/Drupal/Core/DrupalKernel.php(693): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #30 /Users/john/Sites/devdesktop/project/vkp/docroot/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request)) #31 {main}.