Upgrade of 2.4.8 to 3.1

i have ojs 2.4.8 and after a long time that i used that i have big database
now i want upgrade some and selection of publication in my database to version 3.1
how can i upgrade and export data from database 2.4.8 to 3.1 and after transport publication work very well ?!

Hi @mbabaei

When you plan attempting an upgrade, is advisable you make a copy of files and database and run a upgrade in a development environment. Just and only after test and assure everything is working, you should deploy to production.
So, my suggestion is create a test environment machine and upgrade your OJS.
Ask to your editor test this temp install and confirm if is safe to run a final upgrade.
But, always have a backup, it is not possible perform a downgrade in OJS.

Israel Cefrin
Public Knowledge Project Team

thanks dear Israel
but i think u didnt understand exactly my request
i know i have chance to upgrade OJS but when u upgrade systems all publication should be update but its not my willing
i want select for example publication A and F and G and Y, so i need upgrade just these publication
i dont willing upgrade for example B,C,D,E … just my selection publication

could you have any suggestion for me ? and my problem?

Best Regards
M babaei

I think that it is not possible to do upgrade only one part of OJS.