The error message "installer_messages.environment.wizard.form.db_connection_failed" indicates that the installation process was unable to connect to your database. This could be due to several reasons, including incorrect database credentials, an incorrect database host, or a problem with the database server.
To resolve this issue, you will need to check and verify your database configuration. This includes checking the following items:
Database credentials (username and password)
Database host (e.g. localhost, IP address, or domain name)
Database name
Port number (if applicable)
Once you have verified your database configuration, you should test the connection to make sure it is working correctly. You can do this using a tool like phpMyAdmin, or by connecting to the database using a command line tool like MySQL Workbench.
If you are still unable to connect to your database, you may want to try the following troubleshooting steps:
Restart your database server
Check the firewall settings on your server to make sure the database port is open
Check the error logs on your server for more information about the connection failure