This error normally happens right after a new WordPress theme installation or WordPress upgrade. The entire blog is showing a blank page; so is the WordPress admin login page. There’s no way to access the dashboard.
Solution 1: Rename Current Installed Theme Folder Via FTP
Renaming the currently installed theme folder via FTP can force WordPress to choose the default theme to be put into service and you’re able to access WordPress wp-admin after that.
- Navigate to the wp-contents/themes directory via FTP.
- Rename current installed theme folder. For example: “twentytwenty” to “twentytwenty-temp”.
- Login to your WordPress wp-admin.
- Check if your theme is compatible with your version of WordPress.
- Check if your theme contains coding which can’t be executed.
Solution 2: Reset Plugin Folder Via FTP
- Navigate to the wp-contents directory via FTP.
- Rename plugins folder to “plugins-temp”.
- Create a new folder called “plugins” at wp-contents.
- Try to login to your WordPress wp-admin.
- Move your plugin from “plugins-temp” to “plugin” and activate them one by one.
- Check if any plugin is not compatible with your version of WordPress.