Why am I getting ActionController::InvalidAuthenticityToken with every post of my form?

We just rolled out an update to our app which switched to mem_cache_store for sessions. Immediately, all posts to forms threw an ActionController::InvalidAuthenticityToken exception. I understand that there was a problem with this in 2.3.9, but we're on 2.3.10.

The config change in production.rb is:

require_library_or_gem 'memcache'

config.action_controller.session_store = :mem_cache_store
config.action_controller.session = {
  :secure => true,
  :cache => MemCache.new('our.memcache.host', :name开发者_如何学Pythonspace => 'rack:session')
}

Am I doing something wrong?

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You need to rename the session key whenever you move the session store to prevent ActionController::InvalidAuthenticityToken errors.