Topic on Extension talk:ConfirmEdit

When I am upgrading mediawiki1.18 to 1.25.5 I have a question like this:Fatal error: Uncaught exception 'Exception' with message 'E:\wamp\www\wiki/extensions/ConfirmEdit/extension.json does not exist!' in E:\wamp\www\wiki\includes\registration\ExtensionRegistry.php on line 101

What is extension.json and where is it? How to solve it? Thanks

Affirmative, this exension.json stuff is still a mess at the moment. Perhaps it works from MW 1.26 onwards. However, just the "require_once ..." call instead to invoke the extension.