I'm getting this error suddenly on Reviews tab on product details page as:
Fatal error: Uncaught exception 'Exception' with message 'Recoverable Error: Argument 1 passed to Zend_Controller_Plugin_Abstract::setResponse() must be an instance of Zend_Controller_Response_Abstract, instance of Magento\Framework\HTTP\PhpEnvironment\Response given, called in C:\xampp\htdocs\Magento21\vendor\magento\framework\Profiler\Driver\Standard\Output\Firebug.php on line 61 and defined in C:\xampp\htdocs\Magento21\vendor\magento\zendframework1\library\Zend\Controller\Plugin\Abstract.php on line 70' in C:\xampp\htdocs\Magento21\vendor\magento\framework\App\ErrorHandler.php:61 Stack trace: #0 C:\xampp\htdocs\Magento21\vendor\magento\zendframework1\library\Zend\Controller\Plugin\Abstract.php(70): Magento\Framework\App\ErrorHandler->handler(4096, 'Argument 1 pass...', 'C:\xampp\htdocs...', 70, Array) #1 C:\xampp\htdocs\Magento21\vendor\magento\framework\Profiler\Driver\Standard\Output\Firebug.php(61): Zend_Controller_Plugin_Abstract->setResponse(Object(Magento\Framework\HTTP\PhpEnvironment\Response)) #2 C:\xampp\htd in C:\xampp\htdocs\Magento21\vendor\magento\framework\App\ErrorHandler.php on line 61
I'm not sure what this error means and haven't made any changes in the files mentioned in the error.