You can apply "How To Fix Theme Switching Error Message In 2.2.4" to fix it now and remove it after Magento developers fix the core issue.
Change in Magento\Email\Model\AbstractTemplate.php this:
public function setForcedArea($templateId){if ($this->area) {throw new \LogicException(__('Area is already set'));}$this->area = $this->emailConfig->getTemplateArea($templateId);return $this;For this:
public function setForcedArea($templateId){if (!isset($this->area)) {$this->area = $this->emailConfig->getTemplateArea($templateId);}return $this;}Thanks for reading!
