New config setting multi_server_environment=0 was introduced in #10737 - this config setting should be set to 1 when you're using more than one server for your Piwik installation. For example if you are using Piwik in a load balanced environment, if you have configured failover or if you're just using multiple servers in general. By enabling this flag we will for example not allow the installation of a plugin via the UI as a plugin would be only installed on one server, or a config file change would be only made on one server instead of all servers.

-> we should test a bit more this setting, and then document it in a FAQ, as well as mention/link in the load balanced FAQ etc.