I want to upgrade NOP version 3.9 to 4.5

I want to upgrade NOP version 3.9 to 4.5.
Can you please tell me steps by step.

https://docs.nopcommerce.com/en/installation-and-upgrading/upgrading-nopcommerce.html
In a nutshell...
a) make backup of db *
b) apply SQL scripts for each subsequent version from 3.90->4.00, 4.00->4.10...  ->4.3
c) run nopC 4.50 Install, which will do updates "automatically with migrations"

(* You may want to apply updates to the backup, and point the new nopC to that DB, rather than updating your prod system.)

I am able to restored my Database, Thank you.
But can you please tell me how should I restore my Plugins.
And How should I find out which plugin not support version 4.5.

You need to get all new plugins which are compatible with v4.5
Either from the marketplace or the plugin developer

Check the plugins.json file to see the supported versions

The script will also upgrade each plugin's information? Or do I have to configure each one in the 4.5 after installing the plugin for that version?

No, You have to run individual upgrade script for individual plugin.
Some plugin provide give upgrade script along with updated plugin.
Some plugin provider handle it automatically.
So, contact with plugin provider if they have upgrade script or not!

And should I do the upgrade with or without the plugins installed in the initial version (4.10) ?

If you need those plugin then you have to upgrade with those plugin, right?
I would prefer you to upgrade to latest version with default plugins first, then include other plugins 1 by 1, and check if everything okay.

What do you mean by default versions?

patrick_sardinha wrote:
Sorry, i mean to say, default plugins first.