Mysql2::Error: Access denied for user username'@'localhost' (using password: NO)

Is there any reason this would happen in rails 6?

I guess it’s the same reason for any rails version, bad database configuration. Double check your config/database.yml

Tried that I copied from a working database.yml

From your other question, you changed mysql to sqlite, somewhere you still have mysql configured. Look for any mysql reference on your code and remove that.

A lot of people having the same problem Could it be db:schema:load is dep’d in favor of db:migrate? Also I ran rails db:system:change --to=mysql

Now it works