How to fix error in model with gem lockbox

Question

I am using ruby '2.5.9' and rails '4.2.11.3'. I configured all needed things for this gem. I have db with column "password_ciphertext", In model: "has_encrypted :password". When I type "Password" in rails console I have error: "NameError: undefined local variable or method `attributes_to_define_after_schema_loads' for Password"

Can you please explain what I am doing wrong