How to transfer data from Redmine 1.1.1 to Redmine 3.4.7?

Question

Redmine

There is a very old Redmine 1.1.1 (without plugins and improvements). There is a need to migrate to a fresh (with the ability to install the necessary plugins) redmine (the latest 3.4.7). How can this be done?

Answer 1

The 4th one will be out soon. Usually, just standard migrations are enough (if there were no plugins).