ONGR Settings Bundle uses Doctrines PhpFileCache. It works very well, however, it operates correctly only on a single server. If your system uses numerous servers to improve its performance, the FileSystemCache will not be able to clear the cache correctly throughout your architecture.

There are, in essence, two ways that you can fix this. Below is information about both of them.

Overriding the service

First one is simply overriding the cache service. You will need to use a different cache system from Doctrine. More information on that can be found here. Once you've picked a right class for the job, say Memcache, you will need to override the ong_settings.cache_provider in your projects services.yml file. Here is an example of the configuration:

        class: Memcache
            - [ addServer, [ "", 11211 ]]
            - [ addServer, [ "", 11211 ]]
      class: Doctrine\Common\Cache\MemcacheCache
          - [setMemcache, ["@memcache"]]

Writing an event listener

The second option is to write an event listener that would listen to the ONGR\SettingsBundle\Event\Evens::PRE_UPDATE event and would call the ongr:settings:cache:clear command from the other servers. Setting name, that should be provided to the command as an argument, can be fetched from an event.