To troubleshoot, I first installed a fresh instance of SuiteCRM 8 and realized that the database host requires a password. So, I created a new database user, assigned a database to it, and used those credentials during installation. That worked.
Then, I updated my existing dbconfig with the new host and database credentials, and that solved the issue.
Although my previous database connection was working, the host’s password wasn’t set, which might have been causing the problem.