I'm not sure what this error is related to but any advice would be appreciated.

I accessed my website today and the following error was displayed on a white screen.

Fatal error: Uncaught Error: Class "Symfony\Component\ErrorHandler\ThrowableUtils" not found in /home/customer/www/mydomain.com/public_html/libraries/vendor/symfony/error-handler/ErrorHandler.php:563 Stack trace: #0 [internal function]: Symfony\Component\ErrorHandler\ErrorHandler->handleException(Object(Error)) #1 {main} thrown in /home/customer/www/mydomain.com/public_html/libraries/vendor/symfony/error-handler/ErrorHandler.php on line 563

No changes have been made to my site, and I haven't updated anything. It appears to be intermittent, I've checked and it's now online again, but I've made no changes. Not sure why it's not working one minute, then suddenly everything appears ok without any changes made.

I am able to login to the Joomla admin area ok.

When I check the administrator/logs/everything.php the most recent entry is below. I'm not sure if this is relevant?

2023-02-06T10:40:08+00:00   CRITICAL 35.245.189.173 error   Uncaught Throwable of type Exception thrown with message "View not found [name, type, prefix]: page, feed, sppagebuilderView". Stack trace: #0 [ROOT]/libraries/src/MVC/Controller/BaseController.php(602): Joomla\CMS\MVC\Controller\BaseController->getView('page', 'feed', 'sppagebuilderVi...', Array)
#1 [ROOT]/components/com_sppagebuilder/controller.php(81): Joomla\CMS\MVC\Controller\BaseController->display(true, Array)
#2 [ROOT]/libraries/src/MVC/Controller/BaseController.php(672): SppagebuilderController->display()
#3 [ROOT]/components/com_sppagebuilder/sppagebuilder.php(24): Joomla\CMS\MVC\Controller\BaseController->execute('')
#4 [ROOT]/libraries/src/Dispatcher/LegacyComponentDispatcher.php(71): require_once('/home/customer/...')
#5 [ROOT]/libraries/src/Dispatcher/LegacyComponentDispatcher.php(73): Joomla\CMS\Dispatcher\LegacyComponentDispatcher::Joomla\CMS\Dispatcher\{closure}('/home/customer/...')
#6 [ROOT]/libraries/src/Component/ComponentHelper.php(355): Joomla\CMS\Dispatcher\LegacyComponentDispatcher->dispatch()
#7 [ROOT]/libraries/src/Application/SiteApplication.php(200): Joomla\CMS\Component\ComponentHelper::renderComponent('com_sppagebuild...')
#8 [ROOT]/libraries/src/Application/SiteApplication.php(241): Joomla\CMS\Application\SiteApplication->dispatch()
#9 [ROOT]/libraries/src/Application/CMSApplication.php(294): Joomla\CMS\Application\SiteApplication->doExecute()
#10 [ROOT]/includes/app.php(61): Joomla\CMS\Application\CMSApplication->execute()
#11 [ROOT]/index.php(32): require_once('/home/customer/...')
#12 {main}

I'm using Joomla 4.2.5 and PHP 8.0.27

My webhost (siteground) have confirmed everything looks ok at their end, and suggested a restore from backup.

I'm reluctant to upgrade anything until I understand what's going on.

Any ideas?