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