Multistep Validations with Wicked: Validation failed: Street can't be blank

I have a multistep form. It's a bit complicated, cause basically first the user gets created through registrations controller, then get's redirected to a form. Speaking precisely, it's not a multistep form, but more of a two-step registration. To do validations with those is quite triky, but I figured the way, which works. In my User.rb I defined validations as follows:

validates :first_name, presence: true, :on => :create
validates :last_name, presence: true, :on => :create
validates :street, presence: true, :on => :update

But now I am having issues, with showing the errors to a user on that update step. I have the update action in my UserStepsController:

class UserStepsController < ApplicationController
    include Wicked::Wizard
    steps :address
    #respond_to :html, :js

    def show
      @user = current_user || User.from_omniauth(request.env["omniauth.auth"])
      render_wizard
    end


    def update
      @user = current_user || User.from_omniauth(request.env["omniauth.auth"])
        if @user.update!(user_params)
            render_wizard @user
        else
            render :show
        end
    end


    private

    def user_params
        params.require(:user).permit(:email, :password, :password_confirmation, :remember_me, :first_name, :last_name, :street, :house_number, :city, :zip_code)
    end

    def redirect_to_finish_wizard(options = nil, params = nil)
        redirect_to new_user_profile_path(current_user)
    end

end

So, if the User can't be updated, cause the validations have failed, I would love to show error messages about what went wrong. For this in my address.html.erb I defined this behaviour:

<%= form_for @user, url: wizard_path do |f| %>
    <% if @user.errors.any? %>
        <div class="error_explanation">
            <h2><%= pluralize(@user.errors.count, "error") %> prevented this record from being saved:</h2>
                <ul>
                    <% @user.errors.full_messages.each do |message| %>
                        <li><%= message %></li>
                    <% end %>
                </ul>
        </div>
    <% end %>

        <div class="row second 1">
            <div class="column">
              <div class="field wizard">
                <%= f.label :street %><br />
                <%= f.text_field :street, class: 'form-control' %>
              </div>
            </div>

This won't show the errors, but throws active record error instead:

ActiveRecord::RecordInvalid in UserStepsController#update
Validation failed: Street can't be blank

Extracted source (around line #14):

12 def update
13 @user = current_user || User.from_omniauth(request.env["omniauth.auth"])
14 if @user.update!(user_params)
15 render_wizard @user
16 else
17 render :show

What am I doing wrong?

update vs update!. If I remember update! runs save! instead of save on model. It means that it runs exception if record is not valid. update will try to call save method which runs validations