When I started a new project in Rails 7 and copy code from previous project, I encountered the several problems. For example, for login page, if password is wrong, the page doesn't show errors. For signup, similarly, it doesn't show any error messages.

I found JS console error

responses must redirect to another location

Then I found the articles 1 & 2

Here is why:

• In Rails 7, Turbo replaced Turbolinks.
• Turbo requires each response must redirect to another location.

    format.html { render :signup } # same page 
    format.html { flash[:error] = "ERROR" } # same page, no redirect

• There are two solutions:

  • same page, but different status

  format.html { render :signup, status: :unprocessable_entity}
  format.html { flash[:error] = "ERROR"; redirect_to({action: :login})} # redirect to itself. 
  

  • use turbo_frame_tag