Hello.
Since you took a long time to respond, I contacted the creator of the template: He ordered to deactivate all plugins and reinstall the template. It didn’t work and I ended up damaging the aesthetics of the template.
To resolve the failed solution, I restored to a backup copy using the “All-in-One WP Migration” plugin. Even though the backup copy was already made with the error in the database, the problem was resolved. Perhaps because the “All-in-One WP Migration” app reconfigures the database.
