I made a mistake before migrating a plugin, and have written
flash[:notice] = :label_presta_added
flash[:notice] = l(:label_presta_added)
Started GET "/" for 127.0.0.1 at 2016-06-01 22:21:37 +0200
Processing by WelcomeController#index as HTML
Current user: admin (id=1)
Rendered welcome/index.html.erb within layouts/base (28.1ms)
Completed 500 Internal Server Error in 366ms (ActiveRecord: 116.0ms)
ActionView::Template::Error (undefined method `html_safe' for :label_presta_added:Symbol
Did you mean? html_safe?):
97: <div id="sidebar">
98: <%= yield :sidebar %>
99: <%= view_layouts_base_sidebar_hook_response %>
102: <div id="content">
103: <%= render_flash_messages %>
app/helpers/application_helper.rb:312:in `block in render_flash_messages'
This is stored in your session, so usually changing the session secret key will invalidate all sessions and discard any old session data.
You can also try and
rescue to clear it out as a one-time deal.