QuoteUnfortunately Tvheadend does not provide an automatic upgrade or configuration export/import process so 4.0 users must perform a new installation of Tvheadend 4.2. This is inconvenient, but there is no other option.
This information seems incorrect from my point of view. I have found out that a migration is possible and not difficult. With thousands of channels and a complex configuration people should not get told there is no way to upgrade if this works.
Please see How to migrate tvheadend settings from 4.0 to 4.2? for a how-to. I'm not sure why you document this incorrectly. Can you fix this incorrect information or explain what is not working if I may missed something serious, please?