I updated my keys and salts and broke my live or local site!
The wp-config.php file is environment specific, meaning it contains the database name and password, etc., specific to the local or live environment. So you never want to mix up the local and live wp-config files or you will see the white screen of DEATH! <insert spooky music here>
If you are updating the keys and salts for the live site, first make sure you have a recent backup of the site! Then, you'll want to download the live wp-config (you can access it via SFTP), update the keys and salts (editing the file via your text editor), and then upload that same updated file to the live site.
You don't have to update the keys and salts on your the local site, but it can be good practice. Just make sure that you are editing the appropriate (local) wp_config.php file!
If you accidentally overwrite the wp-config file on your live site with the wp-config from your local site (it happens!!) don't panic! If you are using WPEngine, it's super simple. In your WPEngine dashboard, navigate to your
Backup Points, and either restore your site to a previous version, or download a zip of a past restore point, grab the wp-config.php file, and upload it back to the server. Problem solved!
If you are using a host other than WPEngine, grab the wp-config.php file from a backup and upload it back to the server.
If for some reason there is no backup available, you can look up your live site's database information using a tool provided by your hosting company (such as cPanel) and modify the corresponding values in your live wp-config.php file to match. Otherwise, you could call customer support and ask them to restore your wp-config.php file to what it was before.