I am working on magento 2.3.0
When I try to edit a cms page on the admin, the content section is blank, with console error that tinymce is missing or 404. please see attached screenshots.
As you see, your JS files are failed to load, for this case, you can follow the below steps.
Run Static Deploy.
php bin/magento setup:static-content:deploy
Then clear cache.
php bin/magento cache/clear
Then give permission to your cache and pub files.
sudo chmod -R 777 var/ generated/ pub/
After all, this, try to load the CMS page section again. Hope this will do in the most case.
If it's still not fixed, check you might has missed the JS folder.