I would assume that this is some sort of plugin/theme conflict as well. Since WordFence is still working that means that parts of the website are still working.
Can I use my backup because this looks to me like a plugin conflict–your assistance would be appreciated.
If you have a backup of your website before this error happened then it is probably best to restore it. Also if you have a database backup you should restore that as well. Check out this article for some guidance https://www.wpbeginner.com/beginners-guide/beginners-guide-how-to-restore-wordpress-from-backup/
If that backup doesn’t work, or you just can’t understand it then I would try the following.
Try manually resetting your plugins (no Dashboard access required). If that resolves the issue, reactivate each one individually until you find the cause.
If that does not resolve the issue, access your server via SFTP or FTP, or a file manager in your hosting account’s control panel, navigate to /wp-content/themes/
and rename the directory of your currently active theme. This will force the default theme to activate and hopefully rule-out a theme-specific issue (theme functions can interfere like plugins).
One other thing to try is to replace your core files to make sure that they are not corrupted or something.
Try downloading WordPress again, access your server via SFTP or FTP, or a file manager in your hosting account’s control panel, and delete then replace your copies of everything except the wp-config.php
file and the /wp-content/
directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings.
Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.
Good luck,
Matthew