Additional uncaught exception thrown while handling exception.

Original

Error: Class "Symfony\Component\HttpFoundation\Response" not found in include() (line 21 of /mnt/web601/a0/68/510100968/htdocs/EPO9/web/core/lib/Drupal/Core/Form/EnforcedResponse.php).

include() (Line: 576)
{closure:Composer\Autoload\ClassLoader::initializeIncludeClosure():575}() (Line: 427)
Composer\Autoload\ClassLoader->loadClass() (Line: 20)
Drupal\Core\EventSubscriber\EnforcedFormResponseSubscriber->onKernelException() (Line: 254)
Symfony\Component\EventDispatcher\EventDispatcher::{closure:Symfony\Component\EventDispatcher\EventDispatcher::optimizeListeners():249}() (Line: 206)
Symfony\Component\EventDispatcher\EventDispatcher->callListeners() (Line: 56)
Symfony\Component\EventDispatcher\EventDispatcher->dispatch() (Line: 241)
Symfony\Component\HttpKernel\HttpKernel->handleThrowable() (Line: 91)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 30)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 32)
Drupal\big_pipe\StackMiddleware\ContentLength->handle() (Line: 203)
Drupal\page_cache\StackMiddleware\PageCache->fetch() (Line: 140)
Drupal\page_cache\StackMiddleware\PageCache->lookup() (Line: 89)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 71)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 54)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 753)
Drupal\Core\DrupalKernel->handle() (Line: 34)
Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run() (Line: 32)
require('/mnt/web601/a0/68/510100968/htdocs/EPO9/vendor/autoload_runtime.php') (Line: 22)
require_once('/mnt/web601/a0/68/510100968/htdocs/EPO9/web/autoload_runtime.php') (Line: 13)

Additional

Error: Class "Symfony\Component\HttpFoundation\Response" not found in _drupal_log_error() (line 160 of /mnt/web601/a0/68/510100968/htdocs/EPO9/web/core/includes/errors.inc).

_drupal_log_error() (Line: 122)
_drupal_exception_handler()