Rake db:migrate error “don't know how to build task”

Question

I\'ve got a table where I used integer on a field which needs decimal places, so I\'m trying to create a migration which changes the field type from integer to float/real. M

Answer 1

While in this specific instance the stacktrace posted by OP shows the error is trying to do two tasks at once, I found this page after googling and just want to add to the answer for future googlers:

try including either RAILS_ENV=development or RAILS_ENV=test as that is what fixed it for me.