Unable to display 404 pages of WordPress theme

Symptoms: the 404 page of WordPress theme cannot be displayed, but the 404 file default to the host is displayed. If the 404.html file in the root directory of the website is deleted, a blank page is displayed.
To solve this problem, open the pagoda panel → website → site → settings → configuration file, search for "error_page 404/404. html", and add # to the front, for example:

 #error_page 404 /404.html;

Refresh the 404 page of the website. Is the 404 template that comes with the theme displayed? If not, restart the service and save the fixed link settings.