Well, for me this is a question who owns the config file: * If the package owns the file, and the user is not supposed to make changes to it, then package upda

Well, for me this is a question who owns the config file: * If the package owns the file, and the user is not supposed to make changes to it, then package updates may do whatever to the file on update. It's good practice though, to leave a copy of the old file in /lost+found. * If the user is allowed to make modification, then the user owns it. The configuration syntax becomes and API and should be treated as such. Breaking changes should be rare, preceded by a deprecation period and announced as major versions. As you say, it's questionable if such updates can/should be automated.