irb(main):003:0> user = User.find_by :userid => 'admin'
irb(main):004:0> user.password = 'smartvm'
BCrypt::Errors::InvalidHash: invalid hash
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/bcrypt-3.1.11/lib/bcrypt/password.rb:60:in `initialize'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/bcrypt-3.1.11/lib/bcrypt/password.rb:46:in `new'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/bcrypt-3.1.11/lib/bcrypt/password.rb:46:in `create'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/activemodel-5.0.7/lib/active_model/secure_password.rb:118:in `password='
        from (irb):4
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/console.rb:65:in `start'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/console_helper.rb:9:in `start'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/commands_tasks.rb:78:in `console'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
        from /home/milan/.rbenv/versions/2.4.2/lib/ruby/gems/2.4.0/gems/railties-5.0.7/lib/rails/commands.rb:18:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'
irb(main):005:0>