If it’s working then find, if not then…
You can also try clearing your browser cash, closing it then re-opening it.
Here’s an article that explains it better and also has something you can do with the .htaccess file, as well as disabling plugins, make sure you copy the contents of your current .htaccess onto a notepad file or something in case you need to revert back.
The error says the theme cannot access a file needed because it doesn’t have permission. That’s usually a problem with file permissions or .htaccess
If it’s still not working you might need to speak to your host or I can take a look for you.