Best practices and potential landmines in upgrading from 3.80 to 4.40.4 without the original source code

Greetings.

I have been given the task of making an estimate for moving an existing webshop that's running on 3.80, to which to source code has been lost (save for their custom plugin source), to a brand new webshop that's going to use the same database, but a different frontend design, and the code will be source-controlled and safe this time.

I'm in the process of discovery so i can give a better estimate, given that it's my first time working in nopCommerce.

I have managed to upgrade a local backup of their database from 3.80 to 4.40 via SQL (the upgrade to 4.40.4 being handled via code migrations as far as I'm aware) and spin it up over a stock local solution for the latest nopCommerce. It seems to work fine as far as i can tell.

The thing is, they are using some plugins that create tables (for instance, AnywhereSlider, with tables such as SS_AS_AnywhereSlider and SS_AS_SliderImage) to which i don't have access to since they're paid plugins. Are those tables something to worry about or should i just ignore them and let the plugin sort it out?

More generally though, what are some best practices during a process such as this, and are there some notable landmines i need to keep in mind? Most tutorials assume you have the source of the original site you're wanting to upgrade.

how we plan to upgrade:
1. migrate only default nopCommerce data & custom business logic (modified by source code/ plugin with source code version)
2. ask for updated plugin from 3rd party vendor (client will manage those)
3. upgrade plugin data if he ask to do that

rk.menon wrote:

ah, so the process i went through is fine; the plugins should take care of their own data without any consideration from me?
as far as i know, they have no custom functionality outside of their custom plugin, to which i have the source code, thankfully.