How to export tasks from one Redmine and import it into another one?

Added by li ru 9 months ago

Hi there...

In advance I apologize for my English.

I have an account on the domain conditionally "source" with Redmine installed v.3.4.2.
There I have a project with many tasks.
I do not have direct access to the SQL database. I am not the owner of the domain.
The domain administrator "source" has not been contacted for a long time, i.e. I can not get the database dump.
Now I would like to transfer the project to another domain "target", the owner of which is already me. I installed Redmine v3.4.5.
What are the ways to transfer all data from "source" to "target", including tasks, subtasks, comments to tasks, attachemt files, etc.?

I also found the possibility of export via Atom. The resulting XML file at first glance contains all the necessary data, but there is no possibility
execute its import on the domain "target".

I made a search for a suitable plugin for these purposes, but did not find a full one. All very old and also with limited functionality.

I ask for help with the transfer of the project.

Environment:
Redmine version 3.4.6.stable
Ruby version 2.3.7-p456 (2018-03-28) [x86_64-linux]
Rails version 4.2.8
Environment production
Database adapter Mysql2
SCM:
Subversion 1.10.2
Git 2.19.1
Filesystem
Redmine plugins:
redmine_lightbox2 0.4.3
redmine_msteams 0.2.0